This study seeks to assess the relative impact of patent status as a component of pharmaceutical prices while controlling other market and medicine characteristics on the retail prices of oncology medicines in Thailand. Ordinary Least-Squares (OLS) regression model of log prices as a function of supply and demand factors was developed and data fitted to establish the relationship and the effects for each factor. The main finding of the model is that patented status is associated with a price of approximately 144-206% that of an equivalent generic.