We investigated the effects of antihypertensive therapy on serum levels of interleukin-4 using InterTest-4 ELISA in 25 preeclamptic women; 14 were placed on treatment, while 11 were not. Comparison was made with 14 non-preeclamptic pregnant controls. Interleukin-4 levels were significantly lower in the controls than in the treated preeclamptic women (p < 0.001): 68.6 +/- 10.9 versus 106.1 +/- 13.2, 64.7 +/- 9.6 versus 119.8 +/- 11.4, 90.2 +/- 9.1 versus 124.3 +/- 15.7, and 65.6 +/- 3.6 versus 109.7 +/- 11.4 pg/ml, during antepartum, early intrapartum, late intrapartum and postpartum periods, respectively. No significant differences were detected between the therapy and no therapy subgroups (p > 0.05). This shows that antihypertensive therapy has no effect on interleukin-4 levels.