Statural growth and its relationship with degree of renal insufficiency were studied in 42 children and 5 infants with chronic renal failure (CRF). Most of the children had a congenital disease or were already ill in the neonatal period. Average GFR was 34 ml/min/1.73 m2 at the beginning and 16 ml at the end of the follow-up period, which averaged 4.3 years (1 to 12 years). Most patients grew at a normal rate; only 3 out of 42 children (7%) and 3 out of 5 infants lost one standard deviation or more during the follow-up period. No correlation was found between the degree of GFR and growth velocity. Catch-up growth was observed only for a 12-month period in 4 children with a bone age of 7 to 8 years. In 10 out of 11 children who reached puberty while under observation, a normal pubertal growth spurt was observed. Suitable and comprehensive controls and treatment can arrest growth retardation in the great majority of children with CRF after the first few years of life, regardless of their GFR. Achievement of a normal growth pattern in infants with CRF during the first year(s) of life remains a major unsolved problem.