Objective-To establish the frequency of permanent growth failure in juvenile onset inflammatory bowel disease.Design Main outcome measures-Height, weight, body mass index, and sexual maturity.Results-All patients were sexually mature. 67 of the 70 patients examined were of normal height, and three women with Crohn's disease were abnormally short. Weight and body mass index were normal in all patients with ulcerative colitis. Patients with Crohn's disease had significantly lower weight than those with ulcerative colitis (men 66-8 (9.5) kg v 78-4 (13-8) kg, P=0 04; women 51 5 (8.2) kg v 63-0 (12-1) kg, P<0-02) irrespective of disease activity. Body mass index was also significantly lower than the normal distribution (P<0 01). Growth retardation was not mentioned as a problem for any of the 17 patients interviewed only by telephone.Conclusions-Despite growth retardation in the teenage years most young people with inflammatory bowel disease will eventually achieve normal height.Reasons for lower weight in patients with Crohn's disease remain to be established.