Innovation plays a key role in driving progress and responding to the constantly changing economic, social, and technological requirements that modern economies face. This article assesses the innovative efficiency of the 11 post-communist EU member states in order to identify those that have achieved the weakest results in transforming pro-innovation inputs into innovative results. The Data Envelopment Analysis (DEA) method was used to estimate efficiency scores. The study analysed two models: Model A – covering 28 EU member states; and Model B – covering 16 EU countries and 12 countries from Europe, Asia and South America that are more similar in terms of economic development as measured by GDP per capita. The data on the input and output measures come from the 2015-2020 Global Innovation Index (GII) reports. The main findings indicate that among post-communist EU member states, Poland and Lithuania have achieved the lowest DEA-efficiency scores in transforming innovation inputs into innovations.