The aim of the study is to assess the effectiveness of the production factors and the competitiveness of agricultural holdings in the region of Wielkopolska and Silesia, specializing in dairy production depending on the scale of production. To achieve the objective the farms participating in the Polish FADN system between 2010 and 2014 from the Wielkopolska and Silesian region were used. Farm income were clearly differentiated and their size depended on the scale of milk production. The largest income was obtained by farms with a very large scale of production. The income of this group of farms was as much as ten times larger than small-scale farms. The competitiveness index: Wk = 2.12, indicating competitiveness capacity, reached the largest dairy farms, these are farms with 90 hectares, holding about 80 cows with an average yield of 8000 kg of cow milk. On the other hand, in medium – and large-scale farms (20-40 cows), the competitiveness index was 1.4-1.8, these farms are competitively-feasible. Study shows that development opportunities have dairy farms above 20 cows.