Six accessions (three with red-coloured seed coat and three with maroon-coloured seed coat) of jack bean (Canavalia ensiformis L. DC.) were collected from six different agro-climatic regions of South India. They were analysed for their proximate, mineral and amino acid compositions, in vitro protein digestibility (IVPD) and certain antioxidant contents. Amino acid profiles revealed that levels of leucine, lysine and tryptophan in red-coloured seed coat accessions and valine, isoleucine, leucine, lysine and tryptophan of maroon-coloured seed coat accessions of jack bean were found to be deficient; whereas, threonine, phenylalanine, tyrosine, histidine and sulphur containing amino acids of all the six accessions were found to be higher than FAO/WHO requirement pattern. The IVPD of the accessions ranged from 73.12 to 79.18%. Antioxidant substances like phenols, tannins, L-DOPA and trypsin inhibitor contents were also investigated.