The determinants of yam production in Southeastern Nigeria were investigated using a stochastic frontier production function, which incorporates a model of ineffi ciency effects. Farm-level data were collected from a sample of 120 yam farmers in Enugu State and used for the analysis. The results indicate that labour and material inputs are the major factors that infl uence changes in yam output. The effects of selected farmer-specifi c socio-economic characteristics on observed ineffi ciencies among the farmers were also examined. Farmer-specifi c variables, such as education, farming experience and access to credit, were the signifi cant factors implicated for the observed variation ineffi ciency among yam producers.