Eric has made very valid points on the value of a PHd in museum studies. First of all, it's difficult to find a university that would offer it. The one best known is the U. of Leicester in the U.K. Most people earn their doctorate in another specific discipline such as art history, history, or one of the sciences. Some then design the course of study to relate to museums. If you want to be a conservation scientist, there's a fairly new PHd program at the U. of Delaware. Lynne TEather who is director of Museum Studies at the U. of Toronto has a PHd from the U. of Leicester. She is on Museum-L. What is it you want to do in a museum? What kind of a position are you anticipating? That will determine more or less your educational requirements. Good luck!