We have failed to measure the recombination fraction between 9qh and the ABO:AK1 linkage group. Since the total male map distance along chromosome 9 is likely to be at least 120 cM, calculated from male chiasmata counts (Hultén, 1974) they may well not be within measurable distance of each other. ACONs does not lie between ABO and AK1, but there is so little information on this marker from family studies that it could lie almost anywhere else on chromosome 9 and might be within measurable distance of 9qh. The map of chromosome 9 based on studies on families with normal karyotypes is summarized in Fig. 1. We hope to improve this map in a subsequent paper based on observations on families with abnormal karyotypes.