The objective of this study was the application of non-parametric method of data envelopment analysis (DEA) to analyze the efficiency of farmers, discriminate efficient farmers from inefficient ones and to identify wasteful uses of energy for alfalfa production in Hamedan province, Iran. This method was used based on eight energy inputs including human labor, machinery, diesel fuel, fertilizers, farmyard manure, biocide, electricity and seed energy and single output of alfalfa yield. Technical, pure technical, scale and cross efficiencies were calculated using CCR and BCC models for farmers. From this study the following results were obtained: from the total of 80 farmers, considered for the analysis, 46% and 69% were found to be technically and pure technically efficient, respectively. The average values of technical, pure technical and scale efficiency scores of farmers were 0.84, 0.97 and 0.89, respectively. Also, energy saving target ratio for alfalfa production was calculated as 9.4%, indicating that by following the recommendations resulted from this study, about 75.90GJ ha−1 of total input energy could be saved while holding the constant level of alfalfa yield. Moreover the contribution of electricity input from total saving energy was 77.4% which was the highest share followed by chemical fertilizers (15%) and diesel fuel (4%) energy inputs. Optimization of energy use improved the energy use efficiency, energy productivity and net energy by 10.6%, 10.4% and 10.6%, respectively. ► We used a non-parametric method of DEA to analyze the efficiency of alfalfa farmers. ► About 46% of farmers were technically and 69% were pure technically efficient. ► Technical, pure technical and scale efficiency scores were 0.84, 0.97 and 0.89. ► Optimization of energy use improved the energy use efficiency by 9.4%. ► Contribution of electricity input from total saving energy was the highest.