Fifty-six patients with acute glomerulonephritis were studied prospectively during 1984. Their ages ranged from 10 months to 14 years old with the peak age range between 5 to 9 years. Most of them had edema, hypertension, hematuria with or without proteinuria and had low serum complement. Azotemia was found in 45 per cent of the cases. Serologic evidence for streptococcal infection was positive in 68 per cent and only 6 per cent had positive culture. Edema and hypertension were all resolved within 2 weeks. All patients that were followed up had normal serum complement by the 6th week, normal BUN, Scr by one year. The hematuria disappeared by 6 months and proteinuria by 2 months in 50 per cent of the cases. By the 4th year only one patient had microscopic hematuria and mild proteinuria with normal serum creatinine, normotension and no edema. In conclusion, in Thailand AGN is still a common kidney disease in children but with prompt and proper treatment its prognosis is still very good.