Visiting Portorico on H1B which is not stamped

[AkkiJerseyCity]

Hi I am on H1B and my visa is valid till Aug 2016. But I am planning to visit portorico. Do I need a stamped Visa for visiting Portorico.

[MadeinIndia]

I guess you mean Puerto Rico. All flights between Puerto Rico and Mainland US are treated as domestic flights. You should be able to prove your legal status in case anyone asks.