Hyperlipidemia has been reported in some infants with bronchopulmonary dysplasia (BPD) who received thiazides for extended periods. In this prospective, controlled trial, we studied 17 infants with BPD who received diuretic therapy and 26 control infants who did not receive diuretics. Plasma triglycerides, total cholesterol and high-density lipoprotein (HDL) cholesterol were measured enzymatically prior to onset of diuretic therapy in the study group of infants and on the day of recruitment into the study in control infants, and every 2 weeks thereafter. Plasma low-density lipoprotein cholesterol concentrations were calculated. At the end of 4 weeks, plasma lipid concentrations were comparable in both groups of infants except for significantly higher plasma HDL cholesterol concentrations observed in infants who received chlorothiazide (39 +/- 15 vs. 30 +/- 6 mg/dl, p less than 0.05). Short-term administration of chlorothiazide to infants with BPD is not associated with clinically significant changes in plasma lipid concentrations.