It has been observed that similar prints can obtain quite different prices at different auctions within the same auction period. Previous works applying hedonic price technique to determine the formation of auction prices of objects of art have found no conclusive result about the impact of auction houses on final prices. In these studies the object of art has been the unit, and influence of auction houses is analysed by testing whether auction house impact on price is significant or not within a framework of central tendencies. In order to focus on auction houses as a unit we have applied a benchmarking technique, DEA, developed for efficiency studies. Performance indexes are defined and calculated giving an insight into auction house differences difficult to obtain using hedonic price approach.