Leflunomide has excellent antiviral activity against cytomegalovirus (CMV) in animal models and is considerably less expensive than intravenous ganciclovir. We used leflunomide in four consenting renal allograft recipients with symptomatic CMV disease, who were unable to afford ganciclovir and would otherwise remain untreated. This is the first report of efficacy of leflunomide in humans with CMV disease. They received loading dose of 100 mg of leflunomide once daily on days 1-3 and then 20 mg once daily for 3 months. All four patients were followed up three times weekly with physical examination, total leukocyte counts, blood urea and serum creatinine for a minimum period of 6 weeks. None of the patients showed drug related adverse events, alteration in cyclosporine levels, or decreased graft function, except one who developed leucopenia. Preliminary data presented suggests that leflunomide therapy for CMV disease is effective and could be used with careful monitoring in allograft recipients who cannot afford intravenous ganciclovir therapy. The duration of treatment and the role of leflunomide in secondary prophylaxis and in situations of ganciclovir resistance need to be studied further.