Although immature embryos are the most suitable explants to regenerate cereals, their limited availability throughout the year hampers frequent experimentation. In order to circumvent this problem, endosperm-supported mature embryos, which are available throughout the year, are proposed for utilization in cereal tissue culture studies. In the present study, the effect of seed size on in vitro seed germination, seedling growth, callus induction and plant regeneration, as well as the relationships between these parameters, were investigated in three barley (Hordewn vidgare L.) genotypes. Seeds were designated as large or small for each genotype and seed germinations were achieved in Petri dishes between two sheets of pre-wetted filter paper. Germination percentages of seeds, seedling growth rates, shoot and root lengths, and seedling fresh and dry weights were examined. Mature embryos from imbibed and dehulled seeds were aseptically moved slightly with a scalpel. For callus induction, 8 mg 1(-1) 2,4-D dissolved in water, and for plant regeneration, hormone-free MS medium, was utilized. Highest values with respect to seed germination percentage, seedling growth, callus induction and plant regeneration were obtained using large seeds. Rooting of regenerated shoots and plantlet recovery were also successfully achieved. Based on the significant positive correlations observed between all parameters, we concluded that cultures derived from endosperm -supported mature embryos within large seeds should be employed for achieving superior tissue culture response.