The paper aims at identifying and assessing the opinions of farmers concerning the socio-economic benefits from non-agricultural activity they conduct towards their agricultural holding, farming family and rural areas on the territory where these units operate. The empirical material for the paper was provided by surveys carried out in 2011-2012, i.e. questionnaire-based interview, among 210 farmers – owners of individual agricultural holdings – running additional non-agricultural economic activity from the area of south-eastern Poland, namely the following three voivodeships: Świętokrzyskie, Małopolskie and Podkarpackie. The classification of the surveyed farms into two groups, which was based on the conditions of the aforementioned opinions, and analysis of differences in the assessment of benefits between these groups, using the Mann-Whitney test, allowed to define the key determinants of farmers’ opinions on the socio-economic significance of the non-agricultural economic activity they conduct. An important determinant was the share of income from non-agricultural economic activity of farmers in the structure of their family’s sources of income. The surveys showed that, in the opinion of farmers, the higher the ratio for the share, the greater the significance of the analysed socio-economic benefits following from non-agricultural activity conducted by them.