Remission followed prednisolone therapy in 9 out of 21 Nigerian children with the nephrotic syndrome who had highly selective proteinuria (CG/CA less than 15%). Of these, 5 patients have remained well off all treatment during a follow-up of nearly 5 years, 4 have relapsed more than once but have responded to further courses of prednisolone. 3 of 21 with less selective proteinuria also remitted but all relapsed and only one of these has responded again. The other two have relapsed and further courses of prednisolone have not totally abolished their proteinuria though they are asymptomatic and in good health. Toxicity (hypertension, sometimes with encephalopathy and infection) was commoner in the patients with less selective proteinuria treated with steroids than in those with highly selective proteinuria. 3 steroid-sensitive patients who had had repeated relapses became free from relapse off all treatment after a course of cyclophosphamide, given during steroid-maintained remission. All but 2 of the renal biopsies taken were regarded as abnormal. The lesions were less severe in those who responded than in those who did not. There is some evidence to suggest that Plasmodium malariae may be a cause of some of the steroid-sensitive disease, as well as the steroid-resistant.