SUMMARYThe geographical correlations between the incidence of various cancers and the HLA and ABO antigen frequencies are studied. There is, for example, a positive correlation between breast and colorectal carcinoma and AI, B8 and B12 antigens, and a negative one between prostate carcinoma and B12.The role of the HLA system itself or other genes involved in these associations is discussed. This study gives some evidence of a possible genetic background of susceptibility or resistance to cancer.