Personally, I would wait for their reply.

That depends on a few things: do you want the email to be formal or informal? Did your interview say when they would make a decision? Follow up emails can also be a good opportunity to list your skills and qualifications again. The following might be a good starting point: Dear Mr./Ms.....: I appreciate the time you recently took to discuss with me the internship position you currently have open at ..... It was a pleasure speaking with you and I found our conversation extremely informative. As I mentioned during our interview, I am confident that, given the chance, I could contribute a great deal to your overall company objectives and goals. After speaking with you, I believe that I would be a perfect candidate for this internship, because... I am very interested in working for you and look forward to hearing from you once the final decisions are made regarding this position. Please feel free to contact me at any time if further information is needed. My contact details are... Thank you again for your time and consideration. Sincerely,