A couple of days ago, I started noticing that iSync doesn’t properly sync my address book and calendar with my phone. I also noticed that my .mac address book is experiencing the same problem. I noticed this because I deleted some contacts from my AddressBook and they still appear on my phone and .mac address book whenever I sync. To make a long story short, I spent 3 sleepless nights trying to solve the problem. Tonight I finally stumbled on the solution: Make a backup of your ~/Library/Application Support/SyncServices folder then delete the original. Logout of your account then log in. This is needed so that the SyncService will recreate the needed folders. Launch iSync. You might need to remove and re-add your phone. Sync your phone - it should now sync correctly. Open System Preferences > .Mac > Advanced. Click on the “Reset Sync Data...” button. In the popup dialog, choose to overwrite your .Mac data with the data from your machine. When the sync finishes, go to your .mac home in your browser and open your address book. You should click on "Reset" from the selection. Your .mac address book should now reflect the contents of your local address book. Hope this helps.