Nigella sativa L. has industrial, herbal, cosmetic and pharmaceutical uses but has not been adequately characterized for its morpho-physiological traits and yield potential. Considering this a study was designed to conduct field trials on 32 Nigella sativa L. accessions to evaluate and characterize morpho-physiological differences among various accessions, to quantify and compare intra-accession diversity and also to determine relationships among various morpho-physiological traits. Efforts made at such characterization would be helpful in the development of improved accessions. High genetic variation was observed in days to first flower, days to 50% flowers, days to maturity, flowering duration, plant height, biomass, number of branches, number of capsules, root length, 1000 seed weight, grain yield and harvest index indicating the worth of material evaluated. Coefficient of correlation revealed grain yield significantly correlated with plant height during 2003 and 2004 while biomass was significant throughout three years. Moreover, PCA and cluster analysis revealed that selection can be made for individual principal traits.