The observed patterns of segregation of two co-dominant alleles at the macaque albumin locus in 400 rhesus monkey offspring were compared with those expected for five segregating mating phenotypes. Rates of reproductive loss and conception were also compared among females of each albumin phenotype. The common albumin allele in macaques, AlAmac, segregated more frequently than expected when the mother was heterozygous but less frequently than expected when she was homozygous for AlBmac. In both cases, the phenotype identical to that of the mother appeared to be favored. Mothers who were either homozygous for AlAmac or heterozygous were also found to experience higher conception rates than mothers homozygous for AlBmac. It is hypothesized that phenotypic differences in bilirubin binding, and in competitive binding by dietary constituents, by albumin influences both these results and the nonrandom distribution of AlBmac in Asian macaques.