Serum levels of aminotransferases, lactate dehydrogenase, gammaglutamyl transferase, alkaline phosphatase, albumin and conjugated bilirubin, measured in 54 women at a median of 31 months (range 3-101) after pregnancies complicated by the HELLP syndrome, were not elevated. Total bilirubin levels, however, were elevated in 20% of these women; this represents a significant difference from the prevalence in 151 women with a previous normal pregnancy (chi(2) - 12.23, P < 0.001), or in the normal female population (chi(2) = 22.34, P < 0.00001). This raises the possibility that a dysfunction of the bilirubin-conjugating mechanism represents a risk factor for the development of the HELLP syndrome.