Abstract: A 5 x 5 diallel cross experiment on spring wheat varieties namely Shahkar-95, Chakwal-86, Faisalabad-85, Rawal-87 and Pasban-90 was conducted to ascertain the type of gene action involved in the control and expression of some important morpho-physiological traits. Plant height, flag leaf area, leaf venation and epidermal cell size were controlled by additive type of gene action with partial dominance. While the parameters like stomatal frequency and stomata size were controlled by over dominance type of gene action. Epistasis was absent in all the traits