The horizontal and vertical forces acting on three chisel plows having different shank shapes were measured in a sandy loam soil. The shank shape of the first plow was curved, while those of the second and third plows were semi-straight and semi-curved, respectively. The effect of forward speeds and plowing depth upon the horizontal and vertical force measurements were investigated. Soil characteristics, chisel plow specifications and results of tillage experiments were reported. A significant increase in horizontal force (N/shank/cm2) was observed for all the three commercial chisel plows and was proportional to the increase in the forward speed. However, non-significant increase in vertical force (N/shank/cm2) was observed for all the three plows with an increase in the forward speed. The curved shank gave values of horizontal and vertical forces (N/shank/cm2) greater than that of the other shank shapes.