Renal involvement is common in childhood polyarteritis nodosa (PAN), We report a retrospective analysis of the presentation and clinical course of 26 patients with PAN and renal involvement. The mean age was 9.3 years (range 1-14 years) and there were 12 boys and 14 girls. Renal symptoms at presentation were as follows: 3 had isolated proteinuria, 9 had nephritic syndrome, 2 had nephritic and nephrotic components, and 10 had renal failure with one of the above features. Two patients with isolated hypertension were diagnosed by angiography and classified as classical PAN. Patients either received prednisone p.o. alone (n=9), or prednisone plus cyclophosphamide p.o. (n=11), or pulse steroids with prednisone p.o. and cyclophosphamide (n=2); 4 did not receive any treatment. Patients who were given cyclophosphamide had a significantly better outcome than these who did not. We suggest that oral cyclophosphamide therapy and corticosteroids are effective in the treatment of PAN. The overall 1-year and 5-year survival rates of the patients were 72.5% and 60%, respectively. In conclusion renal disease is a serious manifestation of PAN necessitating prompt and aggressive treatment.