The first aim of this study was to measure the efficiency of the R&D sector in the EU countries. The findings have indicated that the sector?s efficiency was different in particular countries. It was more than three times higher in the most efficient states than in the least efficient ones. The results also indicate that decreasing returns to scale are characteristic in the R&D sector in the EU countries. The second aim was to examine the relationship between the efficiency of the R&D sector and the structure of its financing. The empirical results occurred to be consistent with the research hypotheses ? the public sector?s share in the R&D financing structure affects the efficiency of the R&D sector positively, while the private sector?sshare affects it negatively.