We studied the frequency of HLA DR antigens in 96 women whose 50 with preeclampsia (PE = proteinuria greater than 0.5 g/l + HTA) and 46 with gestational HTA (GHTA = pregnancy-induced HTA without proteinuria). Sixty had later pregnancies (28 PE and 32 GHTA) and were followed for from 3 to 23 years (m = 8.5 yrs) after the first pregnancy. HLA DR antigen distribution was determined by a search on B lymphocytes for the 10 antigens of locus DR. The normal population included 38 control couples (76 mothers and fathers) with normotensive pregnancies (A) and 200 healthy controls recruited from a local blood donor population (B). The frequency of alleles was compared to that of the different group of primiparous women and whole group of women with later pregnancies. Significant variations were evaluated by the chi 2 test, using Woolf's method: the p values obtained was multiplied by the number of antigens looked for (p corrected or pc). Only the DR4 antigen, present in 19.7% of control couples (A) and 26.5% of the blood donor population (B), was increased in proportions that depended on clinical classification: 54.3% (pc less than 0.005 with A, less than 0.007 with B) in all primiparous women with GHTA, 38% (NS) in all primiparous women with PE. However significant variation was also observed when the frequency of DR4 in PE women was compared to that in only women of A (38% vs 5.2%, pc less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)