Contrary to what was expected, the structural adjustment of the Polish agricultural sector, observed during the transition which followed the fall of the socialist regime, was a small-scale one: in particular the small farms (7 hectares on average)remained. This study shows that small farms are still prevailing in Poland, not because they are the most technically efficient type of farms, but because the structural change of the sector was constrained by an imperfect functioning of the production factors’ markets . In particular, limited access to credit and the farmers’ pension system may explain this weak restructuring.