We compared mean serum concentrations of meperidine in sickle cell patients in crisis and control patients receiving meperidine prior to incision and drainage of abscesses. Eight sickle cell and five control patients without confounding illnesses consented to participate and received 100 mg meperidine in the deltoid or gluteal muscle for pain. Blood samples were drawn at baseline, 0.25, 0.50, 0.75, 1.0, 1.5, and 2.0 hours postinjection. In the sickle cell group, mean peak concentration of meperidine was 0.32 +/- 0.08 micrograms/mL at an average of 0.5 +/- 0.07 hours postinjection. Among controls mean peak concentration was 0.72 +/- 0.37 micrograms/mL at an average of 0.6 +/- 0.11 hours. The difference in peak concentrations was significant at all time intervals (P less than .01); the difference in times to peak was not significant. We conclude that, given a standard dose, serum concentrations of meperidine differ between sickle cell and control patients, which may suggest reasons for the relatively poor pain control often noted in sickle cell patients.