A procedure of intrafamilial immunization is described for production of antisera recognizing DL-A haplotypes. In a colony consisting of 1 sire, 6 bitches, and 67 offspring all haplotypes could be accurately allocated. In the colony the observed reaction frequencies of the antisera are in agreement with mendelian codominant inheritance. Mixed lymphocyte culture tests confirmed the accuracy of the serologic typing and the presence of homozygous individuals within the colony. Further evidence is presented supporting the presence of two or more subloci within the DL-A system. Colonies of canines such as the one described should provide a sensitive system for evaluating interaction between serologic DL-A typing, MLC reactivity, and immune response genetics in a nonrodent species which is not highly inbred.