We report on 24 children (10 girls) presenting with primary hyperoxaluria. The mean age at diagnosis was 6.3 years (range: 3 months-14.8 years). The mean interval between initial symptom and diagnosis was 1.3 year. The average follow-up period was 22 months (range: 1-60 months). At the time of diagnosis the renal function was normal in 6 children, moderately altered in 1 and severely in 17. During the follow-up the renal function remained stable in 6 patients, improved in 2, deteriorated in 4. The 12 patients with end-stage renal disease at diagnosis remained unchanged. Urolithiasis were present in all patients older than 2 years, and in 1 among the 5 infants. Medullary nephrocalcinosis was observed in 3 patients in whom the renal function was preserved. Diffuse nephrocalcinosis was present in all patients with end-stage renal failure. Improvement of renal function was secondary to stone removal in 2 patients. Extracorporeal shock wave lithotripsy performed in 7 patients was efficient only in 3. In 10 patients oxalate bone disease was correlated with both renal function and dialysis duration, whereas retinal involvement noted in 6 patients was not.