The rapidity of postpartum disease recovery for severe preeclampsia associated with hemolysis, elevated liver enzymes, and low platelet count (HELLP syndrome) has not been well studied. Between January 1980 and March 1989, 158 pregnancies with preeclampsia-eclampsia complicated by HELLP syndrome were managed at the University of Mississippi Medical Center. The 70 patients with platelet nadir below 50,000/microL (class 1 HELLP syndrome) required as long as 11 days for all members to achieve a platelet recovery concentration of more than 100,000/microL, whereas all 88 gravidas with platelet nadir between 50,000-100,000/microL (class 2 HELLP syndrome) exceeded this platelet concentration by the sixth postpartum day, a statistically significant difference (P less than .0001). The interval between delivery and the onset of diuresis (mean +/- SD) was significantly longer in class 1 than in class 2 patients with milder disease (22.7 +/- 18.9 compared with 15.9 +/- 11.1 hours). Significantly more postpartum days were required in class 1 than in class 2 HELLP parturients for the lactic dehydrogenase (LDH) concentration to decrease below 500 IU/L (4.2 +/- 4.9 compared with 3.2 +/- 2.7 days). No women in the class 2 group required plasma exchange therapy to effect disease arrest and reversal, but 11 of 58 severely ill women in class 1 were treated with this modality. We conclude that the platelet count and LDH serum concentration, as indicators of HELLP severity and recovery, are clinically useful tools and that a more protracted postpartum recovery period should be expected for progressively severe expressions of HELLP syndrome.