Abstract: In this study, we propose a hybrid of a stochastic frontier regression. The proposed model and estimation differ from the conventional model of Aigner, Lovell and Schmidt. The model combines a stochastic frontier regression and a random coefficient regression: (a Stochastic Varying Coefficient Frontier Model) (SVCF) to estimate Technical Efficiency (TE) and Single Factor Specific Technical Efficiency (SFTE) of Tunisian farmers for irrigated crops such as: vegetable farming cereal and fruit-trees. The proposed single factor measure of efficiency is based on Kopp’s notion of non-radial technical efficiency and it is shown that in the context of the SVCF model could provide firm-specific estimates even with inflexible production frontiers, such as the Cobb-Douglas. The empirical results indicate that the mean value of technical efficiency for all farms is estimated to be 54.7% for vegetable farming, 67.2% for cereal and 71.2% for fruit-trees. Input specific technical efficiency of irrigated water is under 40% for all crops.