In the initial period of systemic changes, farms with the area of 0–1 ha of arable area were quite an important element of farm structure in Poland, at least from a social point of view. The number of those farms and their share within the farm structure in general varied significantly depending on a region. The farm numbers and structure were changing dramatically in the process of systemic changes, which was more intense than in case of small farms over 1 ha. The number of those farms declined significantly, agricultural production being abandoned or limited. At the same time within that farm sector a dynamic development was observed of a small group of highly specialized market-oriented farms. As a result of statutory change of the definition of a farm, which was introduced in 2012, that group of farms was radically decreased and their structure was changed. This article provides an analysis of changes within the group of farms 0–1 ha throughout the process of systemic changes and integration with the EU against the basic criteria of the new definition of a farm. The new definition excludes farms on which agricultural activity is not pursued as well as farms owned by natural persons (except for organic farms) which produce insignificant amount of agricultural products (the production must reach at least one of the production thresholds defined).