This paper makes an attempt to analyse the factors determining per acre value of output under organic and conventional farming in Nagapattinam district. Further, it has taken into account the organic and inorganic farming under different sizes of land holdings viz., Marginal, Small, Medium and Large farms. Regarding selection of farm households, about 200 farm households have been selected and interviewed for the present study. Among them, 100 farm households are organic farming and the remaining 100 are inorganic farmers. It could be brought out from the conclusion of the study that, it may be brought out the major factors determining the per acre value of output under organic farming are animal labour, electricity, farmyard manure, panchakavya, amirtha karaisal, neem cake, neem oil green manure, and vermi compost. It showed that even one percent increase in use of these inputs lead to increase in per acre value of output under organic farming. Regarding inorganic farming, it could be revealed that human labour, animal labour, electricity, seed, farmyard manure, potassium and neem cake are the major factors determining the increase in per acre value of output in the study region.