Congenital nephrotic syndrome (CNS) can be caused by neonatal infections, renal diseases which exceptionally occur in early infancy and syndromes with a renal histology of DMS. The most common CNS is the Finnish-type (CNF), an autosomal recessively inherited disease characterized by intrauterine onset of massive proteinuria. The CNF gene has been localized to the long arm of chromosome 19, but the pathogenesis remains unclear. Forty-six CNF patients have been treated at our institution. The diagnosis was based on family history, severe proteinuria of intrauterine onset (serum albumin < 10 g/liter at presentation and urinary protein > 20 g/liter when serum albumin was corrected to > 15 g/liter), a large placenta (> 25% of birth wt), exclusion of other CNS-types and normal glomerular filtration rate during the first six months. Treatment included i.v. albumin substitution, optimal nutrition, thyroxine and anticoagulation. Forty-one patients had been nephrectomized bilaterally at a mean age of 1.2 years and after 3 to 25 months on peritoneal dialysis renal transplantation (Tx) had been performed on 34 who were a mean age of 2.2 years. Growth and development has been normal. Patient survival after Tx was 97%, graft survival 94%, 81% and 81% one, three and five years after Tx was (50% cadaver grafts). Mean GFR was 75 ml/min/1.73 m2 after three years, mean height SDS -1.42, and the nine oldest patients attend school in a normal class.