The 1-and 2-year effects of recombinant human GH (rhGH) were evaluated in 80 Japanese children with chronic renal insufficiency (CRI): 32 were on dialysis and 48 were receiving predialysis treatment. The patients were divided into two groups: one was treated with rhGH 0.5 IU/kg/week and the other with rhGH 1.0 IU/kg/week. Mean height velocity (HV) in predialysis children during the year preceding rhGH treatment and during the first and the second year of treatment was 4.4±1.5cm/year, 7.8±1.6 cm/year, and 6.4±2.0 cm/year, respectively, in those treated with rhGH 0.5 IU/kg/week and 4.8±1.4 cm/year, 8.9±2.2 cm/year, and 6.2±1.7 cm/year, respectively, in those treated with rhGH 1.0 IU/kg/week. HV increased significantly during treatment with both rhGH doses compared to pretreatment HV, but the difference between the treatment groups was not significant. In dialysis children, HV did not increase significantly during treatment with 0.5 IU/kg/week of rhGH, but in-creased significantly from 3.6±2.4 cm/year during pretreatment to 7.2±2.2 cm/year and 6.0±1.6cm/year after treatment with 1.0 IU/kg/week of rhGH for one and two years, respectively. From these results the recommended rhGH dose for children on dialysis and predialysis children receiving a supportive treatment is 1.0 IU/kg/week and 0.5 IU/kg/week, respectively.