Although several studies on tuberculous (TB) pleurisy suggest that the addition of corticosteroids to anti-TB therapy may have beneficial effects, these agents are not used routinely. To assess the effects of short-term oral prednisone therapy in TB pleurisy, 74 patients were randomly assigned in a double-blind fashion to treatment with either placebo or prednisone at a dose of 0.75 mg/kg/d for up to 4 weeks with gradual reduction over an additional 2 weeks. All subjects received a standard 3-drug anti-TB chemotherapy regimen for 6 months. TB pleurisy was diagnosed by histologic study and/or culture of pleural biopsy specimens obtained at thoracoscopy. Complete drainage of the effusion was performed simultaneously. Outcome measures were assessed periodically for 24 weeks, including indexes of morbidity and pleural thickening. After randomization, four patients were excluded from the final analysis. Of the 70 patients analyzed, 34 received prednisone and 36 received placebo. Demographic and clinical characteristics of the treatment groups were comparable at the time of hospital admission. Although a statistically significant improvement in symptoms occurred earlier in the prednisone group (8 weeks) than in the placebo group (12 weeks), between-group comparison showed no significant differences at any of the follow-up evaluations. The proportion of subjects in the prednisone group (53.1%) with residual pleural thickening at 6 months did not differ significantly from that of the placebo group (60%). Pleural effusions did not recur in any of the patients. Initial complete drainage of the effusion was associated with greater symptomatic improvement than any subsequent therapy. We conclude that standard anti-TB therapy and early complete drainage is adequate for the treatment of TB pleurisy. The addition of short-term oral prednisone therapy neither results in clinically relevant earlier symptom relief nor confers a beneficial effect on residual pleural thickening.