Deleted contacts come back after syncing

Are the contacts in question in a supported application on your computer? If so, that is why they keep coming back. Delete the contacts in question on your computer.

If your using a Mac then the contacts are saved in Address Book. Depending on how you sync the contacts regardless of whether they are created on your iphone or computer should dissapear when deleted.

From memory in Windows there is a Contacts folder in your My Computer folder so i guess they would be saved there.

I had exactly this issue a couple of weeks back - around the time I upgraded to OS4.

I sync using mobileme and I when I connected up my iphone to itunes I ended up with a ton of old contacts back on my phone - some of which I deleted months ago and were never on my iphone in the first place (but were on address book)!

I also know for a fact that those deleted contacts were not present in Address Book at the time of the iphone duplication so it couldnt have been because they were on AB but not on my iphone - so I have spent a while going through all my contacts and deleting the duplicate contacts of those I used and completely deleting up to 3 of each contacts i no longer use and deleted months ago!