Automatic Visa Revalidation

Officially, you need a new H1B visa stamp to reenter US because you have changed status. However, some poeple can come back with situation similar to yours with valid I94. You can refer to my old posting regrading this issue. Just be careful, if you decide to go any way. Make sure you bring all your current documents, i.e., I797, I94, etc. Probably you need to argue politely with the IO at the border if you were asked for new H1B visa. If you have a plan to travel to China in the near future, you;d better go get a H1B visa at US consulate in Canada.