Lymphocytes of 77 adults with various forms of hematologic malignancy were typed for HL-A antigens. There was an increase in HL-A5 and HL-A13 antigens in the patients with lymphoproliferative neoplasms, as well as in those with myeloproliferative disorders, but the results must be interpreted with great caution. No other gross disorders of phenotype distribution were observed.