Five erythrocyte proteins (Adenosine deaminase, Ada; 6-Phosphogluconate dehydrogenase, Pgd; Esterase 1, Es-1; Esterase 3, Es-3; NADH-Diaphorase 2, Dia-2) and a serum beta-globulin protein (Esterase 7, Est-7) were studied in rabbits using starch gel electrophoresis. Samples were obtained from 317 Spanish Common individuals (38 families, 317 individuals). For the analyses of linkage, Morton's sequential probability ratio test was applied. Clear evidence for linkage between Es-1 and Est-7 (theta 0.2) was obtained, and no evidence of linkage was obtained for the remaining pairwise combinations of loci studied.