Persistent horizontal lines appear on iMac screen

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Happening the same to me. I was working on my M1 (2021) iMac when out of a sudden the horizontal lines appeared flickering in the bottom of my screen, and they are remained there since, covering the dock.

I've hit the Me Too, and sent Apple a report... i hope they do something!

Same problem for me. Today I used the computer for an hour in the morning then looked at my screen's wallpaper, noticed the image was pixelated. Very odd. Hadn't seen that before. Restarted the computer, then this problem started - on the lower 1/3 of my screen, with a little bit of flickering. Bought my M1 iMac 2021.7.24, always turn on air conditioning & or a small portable fan behind the screen if I notice the cord getting hot. I haven't noticed a hot screen like other people on this thread.

I have had the same issue starting September 28 2025.

I took my M1 iMac into the genius bar and left it for inspection. It has always been in a dry, dust-free environment in my small office without issues. I was told it would be $550 or so for repairs and perhaps another $90 in labor. I can't use my business mac like this, and the use of another monitor has made my eyes worse in the past two weeks. Photos attached.

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The same issue started for me yesterday. For right now it's only a few lines at the bottom of the screen, but it sounds like it can get worse. I have an M1 iMac from 2021, and I've always taken good care of it. It's really sad that there isn't a fix for this yet. 😢

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Does anyone know if this is a degenerating problem which will get worse over time, or is the area covered by the lines staying the same? So far, only a relatively small portion of my screen is affected, and I'm wondering if it will get worse as time goes by...

what?

you mean " She also told me that I have to stop using my iMac now " Than how One going to use for work ? If some only just own one computer that is the iMac.

curious how your lines spread the time frame...

Currently my line appear at the bottom , I still can use easy for my eyes at least as I drag the browser up but I do suspect worry the Lines will spread to entire screen just matter of time...

I read through this link. Thank you to all that put so much effort into explaining the problem. I just spent a few hrs on with chat and by phone with tech support. I got ZERO help. This is OBVIOUSLY a mfg problem and apparently well documented. Yet Apple continues to ignore the issue. This was my first apple product any my last. What a disappointment. I will continue to monitor this link and others. In the mean time looks like I will be spreading the word about the integrity of the company.

That’s amazing to hear! Thanks so much for sharing your experience. Super helpful! Just wondering, did Apple ask you to provide your purchase receipt during the process, or did they handle everything based on the serial number alone?

I am now experiencing the exact same issue reported by others here. My M1 iMac is only 3.5 years old, and today it just started doing this:

It has gotten worst since this afternoon, spreading over about half od the screen along with one lone line by itself. Rebooting did not help. I have since plugged in an external monitor, and that is working as it should.

I am having the same issue with my iMac with M1 processor. One night the screen suddenly started to flick and persistent horizontal black lines started to show on the screen. After a few days, these lines disappear but they came back recently and are persistent now. I also noticed that the top right corner of the screen became very hot. I am not sure whether they are related.

Same thing happened to me, Apple Support was next to useless. Said it wasn't currently on their radar as a consistent issue with this computer so they wouldn't cover it and I would have to pay upwards of $1000 to have it replaced. This computer is heating up to the degree that I burnt my finger and if anything were to be touching that part of the screen I have no doubt it would catch on fire. Very disappointed with Apples attention to this issue, especially since it is a hardware issue for many users and not user damage. Will not be purchasing another iMac, that's for sure.

This is Purely just " Luck " in the sense , Apple support. Yeah some get replacement " just for this case " but Apple still don't deny this line problem is cause by themself come design etc. Ever since from M1 now to M4 users also encounter.

Not been negative , Despite the screen been changed. After One year or just this Lines Suddenly appear thing will reappear. Even Tech who repair , fix Apple products for years already highlighted is Apple design flaws and weird why they use back the same stuffs. They claim " maybe Apple just happen get low quality parts or whatever " but summary is Even the screen been replace, the Lines problem will reappear.

I feel some managed to get free screen replace, faster trying to sell it off.

Loreley Community,

For me it's not sooo bad, but the lines happens in the last 10 lines of the screen.

I contact the service line and they told me to wipe away my dust from the screen.. DOH

This is now 2 Month away and nothing happens.. the lines are still there and I have confirmed with that.

What Im ****** on is, that the operators think, we are dump.

Im not so confirm in writing englisch, im from Austria.

My Mac 24", M1, 2TB SSD is from 2022.

I Have this failure since 3.3.2025.

What should I do?

We need, that Apple produce a Incall for these faulty System.

It's a costly fix for a problem that only occurred due to a faulty bit of design/engineering from Apple.

Even if we did do the display replacement it won't be a permanent fix as the same problem will come back eventually. It happened to me.

And since the iMac is somewhat of a niche product Apple will employ it's tried and tested formula; Ignore the complaints until we go away. Eventually Apple may even offer an 'acknowledgement' of this issue but it will count jack-squat for those of us affected.

And as for long time iMac users like myself, I will have to think long and hard before purchasing another iMac (which I prob won't) or even purchasing another Apple product.