Genes encoding seven monoclonal antibody-defined cell-surface antigens have been regionally mapped on human chromosome 11, and compared to those of the AL complex defined by polyclonal antibodies using mutational analysis. MIC1, encoding W6/34 antigen, is probably identical to S1, previously mapped to 11pter-p13. MDU1 and MIC8, encoding 4F2 and TRA-1.10 antigens, respectively, are probably identical to S2(a4) and map to 11q13-q22. MIC9, which governs expression of 4D12 and 2E2 antigens, and maps to 11q22-qter, is not related to any of the five AL genes. MIC4 and MIC11, both mapping to 11pter-p13, may have some relationship to S3 and S1, respectively, but identity has not been proven.