The 1996 annual report of the Chronic Renal Insufficiency Arm of the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) summarizes descriptive data and highlights important features on 1,725 patients from 130 centers. This database contains information on patients with an estimated glomerular filtration rate (GFR) < or = 75 ml/min per 1.73 m2 as calculated by the Schwartz formula, who were treated on or after 1 January 1994. Thus this report reflects 2 years of data entry. Analysis of the data revealed that nearly two-thirds of patients registered had a structural anomaly. On average, patients were 1.5 standard deviations below age- and sex-specific norms for height, and 0.6 standard deviations below weight norms. Mean serum creatinine for the entire group was 2.4 mg/dl and 68% of patients had a baseline GFR of at least 25 ml/min per 1.73 m2. The mean hematocrit for all children at registration was 33.3 +/- 6.3%, and did not vary among age groups. Overall, 30.9% of patients had a hematocrit < 30%. Only 12.8% of patients were receiving Epoetin therapy. Although still in infancy, the Chronic Renal Insufficiency Arm of the NAPRTCS database in providing important insights into this disorder.