In the present article — based on questionnaire research carried out in SGGW- -AR in 1987 — the author undertakes an attempt to distinguish the factors influencing the level of income from agricultural activity and to determine quantitative impact of these factors on the growth of income of a farm in different area groups. The selection of explanatory variables was based on correlation analysis and step regression. The research indicates that the income of a farm depends on the growth of production factors and relations between them, and on the efficiency of their exploitation. The basic factors shaping the income of a farm in all area groups are the cost of mineral fertilizers and lime as well as the value of basic flock and the rate of botanization of land. Additionally, in farms larger than 5 ha to these factors belong the value of agricultural machinery and equipment and the value of feeding stuff. Besides, it can be observed that in the growth of income the importance of land (area and quality), agricultural machinery and equipment and the expenses on feeding stuffs, energy, the value of basic flock and the number of full-time employees decreases with the increase in the area of a farm. The results indicate that in order to increase the income of a farm it is necessary to decrease gradually the resources of labour and to increase the area of a farm and its technical equipment with the simultaneous increase of outlays on turnover means (such as fertilizers and lime). At the same time the above conditions are indispensable for structural changes in the private sector of agriculture Digitalizacja i deponowanie archiwalnych zeszytów RPEiS sfinansowane przez MNiSW w ramach realizacji umowy nr 541/P-DUN/2016