This study analyzes productivity differentials between men and women in the peasant agriculture in Nepal. Both Cobb-Douglas and translog production functions are estimated using data from the Nepal Living Standard Survey 2003/04. Evidence is found for higher value of marginal product of adult family male than adult female, while marginal products of other inputs are found to be relatively higher than the prevailing market wages and prices, implying that these inputs have become gradually a binding constraint in production. Male managed farms produce more output per hectare with higher command in market input use, obtaining credit, and receiving agricultural extension services than female managed farms. In contrast, the result does not clearly support the hypothesis of separability or aggregation of male and female labour, but there is little justification of weak separability. Moreover, head’s sex as proxy for farm manager does not show any difference between male and female managed farms. However, the coefficients of location and household characteristics show significant variations in farm output among ethnic and caste groups residing in different ecological belts of Nepal. Overall, adult male labour is found to contribute more in production process than adult female labour.