India is the second largest producer of vegetables in the world next only to China. The Onion is the major vegetable crop of Rajasthan. The present investigation was carried out to study the cost of cultivation and returns on different cost concepts basis of Onion. The study was conducted in Jodhpur and Nagaur which were selected on the basis of highest area and production of Onion. A sample of 50 Onion growing farmers from different land size categories was selected by probability proportion to number of farmers in each size group. Cost of cultivation of onion vegetables on the sample farms in Jodhpur and Nagaur district. Production is normally considered as the function of area and yield. The decision regarding the choice of crop enterprise to be taken on the farm and the allocation of area and resources under it depends to a great extent, on level of yield, price of output and the cost of inputs used in the production of that crop. The cost of cultivation and the returns to different factors of production help in decision making about the selection of crop and hence, these measures were worked out for onion. On an average, ` 77850 was spent on onion per hectare. Cost of cultivation of large farm category was highest, ` 91595, followed by medium farms (` 83689) and small farms (` 72258). Among the different components of cost of cultivation, human labour accounted for the largest portion (28.45 per cent) followed by seed (17.43 per cent). The other major components were rental value of land (12.85 per cent), irrigation charges (11.92 per cent), FYM (9.52 per cent), PP chemical (5.87 per cent), fertilizers (5.20 per cent) and machinery (3.22 per cent). The cultivation of onion requires more labour use for harvesting and cutting, application of irrigation and transplanting/sowing and as such the share of human labour accounted for the highest share of ` 22456 per hectare (28.85%). Large farmers spent ` 12835 on manures and fertilizers, which was higher than that of medium (` 12134) and small farmers category

(` 10853).