Changes in the broadly understood structure of rural households are largely attributable to the systemic transformation, but mainly to the adjustment of households to the market economy conditions. Generally, it can be stated that agriculture as a whole and also most farms, especially the smaller ones, have proved to be weak entities in the conditions of free competition on the market. The profitability of agricultural production has diminished considerably. In addition, the state-owned farms were put to a restrictive restructuring and privatisation process imposed from the top, whereas farming co-operatives became subject to decollectivisation. Serious changes occurred as a result both in the ownership and legal-organisational structure of farms in 1990-2002. The private sector in the Polish agriculture has clearly become larger and stronger, which relates in particular to individual farms. The share of farming co-operatives in the structure of farms has diminished significantly. On the basis of assets of some former state-run farms (although not exclusively) a dynamic group of relatively large farms has been created, which represent new organisational-legal and ownership forms. The sector of state-run farms has been significantly reduced, mainly as far as the sphere of production is concerned. The formal number of farms is decreasing, although at a slower rate than it could be expected. However, the tough rules of the agricultural market are leading to a fast reduction in the actual number of farms-entities operating on the market. A considerable part of the farms has abandoned production or produces goods for the owners' needs exclusively. The pace of changes in the structure of farms by size is accelerating. The processes of polarisation are intensifying not only as far as the acreage of farms is concerned but also, or even more clearly, as far as their production potential goes. Practically, only larger farms are developing and becoming stronger. This is true, in particular, of farms with the area of 30 -200 ha. In this group of farms there continues a clearly observable process of restructuring and modernisation based on extended reproduction of fixed assets. This group is also characterised by a fast improvement in the age and educational (farming qualifications included) structure of farms. This group of farms also plays an ever more important role in restructuring and modernisation of the Polish agriculture. The excessively high proportion of farms that make no investments at all and the low level of investment outlays in general can be described as very negative phenomena. The principal factors that hampered and still hamper positive changes in the structure of farms are the excessively high and continually growing potential labour resources in agriculture and the extremely low profitability of agricultural production that translates into minimal possibilities of accumulation.