The prevalence of class I and class II HLA antigen was analyzed in 14 patients (12 males, two females) with Whipple's disease, diagnosed an average of 9.7 yr (range 6 months to 25 yr) before the typing. They were compared with 174 healthy control subjects of the same geographic area in Argentina. Class I antigens (locus A, B, C) were studied by lymphocytotoxic test, and class II antigens (locus DR, DQ) were detected by the double immunofluorescence technique. HLA-B27 was positive in one patient (7.7%) and in 4% of the control population. No significant association was found with the antigens tested. We observed no difference in the clinical picture or in the frequency of arthralgias, compared with those reported in the literature. Our data suggest that there is no conclusive proof of an association between HLA-B27 and Whipple's disease.