The use of zero tillage for crop production reduces the time and power requirements for soil preparation as well as the cost. Soil physical properties are altered by tillage operations. A comparative evaluation of zero and conventional tillage was made by studying the soil physical properties to determine their response to both tillage systems. Soil moisture content, soil aeration, soil strength, soil temperature, crop emergence and crop yields were the factors used in evaluating the tillage operations. The comparisons were made in Manitoba on a loamy sand soil at Carman a sandy loam soil at Portage la Prairie and a clay soil at Sanford. Wheat, barley, flax and rape were planted in zero and conventional tillage plots. Conventional tillage operations were discing or cultivating followed by harrowing. The soil moisture content was determined by the gravimetric method. Soil aeration was evaluated by measuring oxygen diffusion rate, air-filled porosity and total soil porosity. Soil strength was compared by measuring soil resistance to penetration and soil bulk density. Soil temperature was measured by copper-constantan thermocouples. Soil moisture content, soil strength and soil temperature were generally higher under zero tillage. Soil aeration was significantly lower under zero tillage in the top soil layer (0 to 3 inch). Crop emergence and crop yield under zero tillage were generally higher than under conventional tillage. The changes in soil physical properties, affected by zero tillage, did not have an adverse effect on crop production for the conditions of this study.