Poland has both farms that engage in many-sided agricultural production and farms that specialise in a single type of production. The former are exposed to a lower risk in their operation whereas the latter have greater chances to reduce, for example, the management costs. The authors of the article has compared the efficiency achieved in the 2004-2005 period by mixed farms, engaging in the plant and animal production, and fruit-growing farms with the economic size of 8-16 ESU. The relevant calculations have been made on the basis of materials obtained through the monitoring of the Polish Farm Accounting Data Network. The conducted comparison has made it possible to state that in the year of Poland's accession to the European Union and in the following year the specialised farms operated more effectively than the farms engaging in many-sided production. Thus, it can be expected that the share of specialised farms in the total number of Polish farms will increase, helping to diminish the gap in this respect between Polish agriculture and agriculture of the remaining EU countries.