In this study, serological HLA-DR and -DQ typing results were compared to typing results obtained with sequence-specific primers in the polymerase chain reaction (PCR-SSP). HLA-DR typing was performed on a random caucasian population consisting of 31 patients and 73 healthy individuals. Considering HLA-DR1-10, differences in typing results were found in 3 out of 73 healthy individuals and 8 out of 31 patients. When HLA-DR1-16 alleles were taken into account, differences in typing results were found in 11 out of 31 patients and 14 out of 73 healthy individuals. Typing results of PCR-SSP, different from that of serology, were all confirmed by sequencing-based typing of HLA-DRB1 alleles. HLA-DQ1-3 typings were performed on 40 individuals consisting of 17 patients and 23 healthy individuals. Differences in typing results were found in 5 out of 17 patients and 1 out of 23 healthy individuals. From the results of this study it can be concluded that serology is a reliable technique, when restricted to identification of HLA-DR1-10 and HLA-DQ1-3 antigens in healthy individuals. By PCR-SSP, however, reliable HLA-DR1-16 and -DQ1-3 typings can be obtained both in patients and healthy individuals.