Environmental protection policy is a widely discussed issue in scientific works. However, special attention should be also paid to the effectiveness of expenditures on environmental protection, and this is the main goal of this paper. The countries of the European Union were selected for this analysis due to the fact that, in recent years, this region has become an informal world leader with respect to the implementation of policy measures in the field of environmental protection. For that reason, the data envelopment analysis methodology was used, which allows the calculation of input-output efficiency for the years 2005–2015. The analysis shows that, among the 30 analyzed countries, the most effective in environmental protection actions is Finland. The hypothesis that higher environmental protection expenditures does not result in better environmental results has been confirmed. Our analysis confirmed the problem of the deteriorating efficiency of environmental expenditures across the selected European Union Member States, caused by increases in spending. This research may contribute to the discussion on environmental protection policy design and its assessment, as well as environmental policy results measurement.