Seven blackgram (Vigna mungo L. Hepper) genotypes were tested for 10 physical characters which determine seed quality. There were significant variations between genotypes for 100 seed weight and volume before and after soaking, hydration capacity, swelling capacity, hydration index and swelling index. Variation of soaked seed density was low. TU-94-2 exhibited best seed quality among the genotypes. Swelling index was positively and significantly correlated with dry seed density and swelling capacity. Swelling capacity was also positively associated with 100 seed weight after soaking and hydration capacity. Path analysis, however, showed that swelling capacity and hydration capacity had high positive direct effect on swelling index, important for cooking quality. The study suggested that selection of swelling capacity and hydration capacity must be given preference along with optimum dry seed density in breeding for grain quality improvement.