The inheritance of seed α-amylase inhibitor in the common bean and the genetic relationships among the variants and six arcelin variants in the common bean were investigated by crossing between accessions containing different αAI and arcelin variants. All seed proteins in parental, F1 and F2 seeds from the crosses were examined by Western-blot analysis. All F1 seeds gave combined αAI banding patterns from parents on the blotting membranes. The segregation of F2 seeds for αAI variants indicated that the polypeptides of αAI variants were inherited as single co-dominant units. Moreover, αAI and arcelin behaved as a single block in crosses, indicating a close linkage relationship between the genes controlling these proteins.