After graduation, I worked a couple years before going back to grad school. I hadn't taken the GRE's, when I decided, on short notice, to go back to school. They took me in provisionally - I took classes, but I was not in a degree program. After a year, they just relabelled me as a PhD candidate. I never did take the GREs. I don't think it was a special property of the scool I attended (Catholic University), rather, I think many scools will make exceptions. I didn't even have particularly good undergrad grades, though I had done some good research after getting my BS.
Thanks Njorl for your quick response.I am a grad student in physics and planning to do PhD next fall.I am looking for some PhD schools in coming years.I don't have time to prepare GRE exam.Thats why I am looking such schools who will waive GRE requirements.