Data regarding pre-harvest energy use and crop yield of 855 farmers of six villages from five different agro-climatic zones of Punjab state, collected for two years, were analyzed statistically. Different mathematical relationships were fitted between the yield of wheat crop and pre-harvest energy use for different categories of farmers. It was observed that Neldor＇s relationship was the best fit on marginal and small farms. Robb＇s parabolic relationship was the best fit on the medium and large categories of farms.