The article presents technical efficiency of the use of production resources for the research sample of the Polish FADN, representing the general population of agricultural holdings, representing over 90% of domestic commercial production. The impact of the size of activity measured by the utilised agricultural area and standard output (economic size), and of the production type on the efficiency was examined. In all cases, non-linear relationships were found, and the technical efficiency curve for grouping characteristics based on the size of the activity took the U shape. Therefore, deviations from the shape of these relations observed in numerous studies may result not only from the selection of the measurement method, but also from the lack of representativeness for the entire agrarian structure of researched farms. Assessing the impact of production orientation on technical efficiency without taking into account the diversity of groups in terms of the size of activity, especially with different assignments to different classes of economic size, in many cases may lead to erroneous conclusions.