In several years leading up to and in the year of the accession, Polish agriculture has seen a rapid growth in the agricultural production efficiency, followed by its slow decline. The article identifies the reasons for this phenomenon. In the first of these subperiods, there was considerable economic freedom and an increase in support for farms, granted mainly by the domestic funds. In the years after 2004, the situation changed. The amounts of aid funds increased, so did the environmental and consumer health and animal welfare requirements to be met by farmers being beneficiaries of subsidies. In addition, larger farms also reduced their economic activity due to the degression in subsidy rates. It is also probable that some agricultural producers have been mainly focused on using subsidies and this phenomenon was accompanied by a decrease in interest in improving the agricultural production efficiency. Some arguments contained in the article were based on estimates. They are rationally substantiated, but according to the author, the article should be considered as preliminary analysis of the topic.