The serum level of interleukin-2 receptor (sIl-2R) and CD-8 antigen were determined as basic parameter in terms of the stimulation of the t-cell mediated immune reaction in patients suffering from pre-eclampsia (n = 21), HELLP syndrome (n = 12) and pre-existing hypertension (n = 10). The data were compared with those of healthy nonpregnant female volunteers (n = 10) and normotensive pregnant women in the course of pregnancy. Hypertension in pregnancy was associated with an increase of sIl-2R and sCD-8 levels depending on the severity of the hypertensive disorder. In the group of patients with severe pre-eclampsia the median of sIl-2R serum level increased from 370 U/ml (normotensive patients) to 730 U/ml and that of sCD-8 from 640 U/ml to 1100 U/ml. In patients with pre-existing hypertension there was a smaller increase of sIl-2R (median 520 U/ml) and decrease of sCD-8 (median 520 U/ml). 6 to 8 weeks after delivery in the group of hypertensive patients the sIl-2R levels were normalized and the levels of sCD-8 were elevated (median 1030 U/ml). The results support the hypothesis of T-cell mediated immunological reactions as pathogenetic factors of the genesis of the hypertensive disorders in pregnancy.