i phone calendar not syncing with imac

That's unfortunate.

If you want help, provide some details of specifically what is happening or not happening. We're not mind readers.

I am having this issue too since I downloaded Mountain Lion on my iMac. I have an iPhone 4S. My wife has an iPhone 4. We do not sync our calendars through iCloud but just through iTunes wirelessly. It had always worked smoothly until downloading Mountain Lion. Now any changes made on phone do not transfer to iMac calendar and any changes made on iMac in Calendar app do not transfer to the iPhones.

Me too. Calendar on my iphone wont sync to calendar on mackbook after installing Mountain Lion. It does sync from my mb to the iphone. I first noticed it wasn't syncing properly after doing a wireless sync through itunes. During testing, I noticed calendar events made on mb showed up instantly on my iphone even when it wasn't connected to power but I couldn't get events made on my iphone to show up on my mb wirelessly or when connected through USB and sncing through itunes. I know I must be missing something. Notes works both ways.

Same thing here. Always synced perfectly with Lion. Just synced after Mountain Lion upgrade, and nothing is changing on calendar. If I find out something I'll be back. Good luck to all.

Update to my earlier post:

I got it to work now...since it wasn't working to sync through iTunes I decided to try using iCloud for the calendars. That was a disaster. Since we have some shared calendars that sync to both our iPhones iCloud duplicated all those events. I eventually decided to forget iCloud because it was too frsutrating so I went back to syncing the old way through iTunes and it started working just fine and has been working fine since 🙂

Many thanks for your tips. It helped!

What tips? Provision syncing thorugh iCloud then unprovision it? I too had a horrible debacle, with contacts in iCloud, and do not want to go back.