The major pathology in sickle cell anaemia (SCA) is sickling of red cells due to the precipitation of reduced haemoglobin. We report our experience with extract of Cajanus cajan as a possible antisickling agent by determining changes, if any, in clinical and laboratory features of the disease in patients given the extract in a single-blind placebo-controlled study. One hundred patients with steady-state SCA were randomized into treatment and placebo arms. The extract/placebo were administered twice daily to the subjects. Weight, hepatosplenomegaly, blood levels of biliurubin, urea, creatinine, and packed cell volume (PCV) were monitored over a 6-month period. Recall episodes of pain 6 months before enrolment were compared with episodes of pains recorded during the treatment period. Twenty-six cases (55.3 per cent) had hepatomegaly on enrolment. This significantly reduced to 33.3 per cent at 6 months (p = 0.03); but increased in the placebo arm (p > 0.05). The total number of recall painful episodes in cases was 207 (mean 4.4 +/- 10.3 (SD), range 0-60) and fell to 191 (mean 4.2 +/- 4.4 (SD), range 0-16); p = 0.03. Episodes of pain increased from 109 in controls (mean 2.6 +/- 5.0 (SD), range 0-26) to 164 (mean 3.9 +/- 4.3 (SD), range 0-22); p = 0.01. Mean PCV in the cases showed no appreciable changes (p = 0.1) but there was a significant increase in the controls (p = 0.02). In conclusion, the extract may cause a reduction of painful crises and may ameliorate the adverse effects of sickle cell anaemia on the liver. The mechanism of action remains to be determined.