This paper studies price determination in pharmaceutical markets using data for 25 countries, six years and a comprehensive list of products from the MIDAS IMS database. We show that market power and the quality of the product has a significantly positive impact of prices. The nationality of the producer appears to have a small and often insignificant impact on prices, which suggests that countries which regulates prices have relatively little power to do it in a way that advances narrow national interest. We produce a theoretical explanation for this phenomenon based on the fact that low negotiated prices in a country would have a knock-on effect in other markets, and is thus strongly resisted by producers. Another key finding is that the U.S. has prices that are not significantly higher than those of countries with similar income levels. This, together with the former observation on the effect of the nationality of producers casts doubt on the ability of countries to pursue "free-riding" regulation.This study was supported by an unrestricted educational grant from the Merck Company Foundation, the philanthropic arm of Merck & Co. Inc., Whitehouse Station, NJ. Partial funding was also obtained from the Spanish Ministry of Science and Technology under grants SEC2003-03474 and SEJ2005-08783-C04-01.