This study investigated the returns to legumes (common bean and soybean) and other principal crops (cassava, sweet potato and maize) in South Kivu, Eastern Democratic Republic of Congo. Data were collected using a structured questionnaire from a randomly selected sample of 291 farmers who had participated in N2Africa project in the four Eastern D. R. Congo territories: Kabare (103), Kalehe (52), Mwenga (24) and Walungu (112). Gross margin and return on capital analysis were calculated. The study found that common bean had the highest gross margin [985,708 FC ha-1 (909FC = 1USD as at June 2013)] and return on labour capital (2.1 FC) compared to other principal crop enterprises. From this study, it was evident that crop enterprises had varying returns on capital which was an indicator of the differences in the importance of these crops from one territory to another. Therefore, the study recommends that as much as legume production is being promoted, the government and NGOs should also emphasize the importance of farm enterprise diversification in the study area.