Background: Growth impairment during childhood and adolescence is a common problem faced by patients with an early onset of Crohn's disease. Aims: To establish how the final adult height is affected in patients with early onset of symptoms of Crohn's disease. Methods: Information on height, parental height, and disease history was obtained from 135 patients with Crohn's disease who reached their adult height (men 22-40 years, women 18-40 years) using a questionnaire and by outpatient measurement of height where possible. Subsequently, adult heights were expressed as standard deviation scores, with and without correction for the expected target height. Results: Patients with onset of disease before puberty were shorter compared with patients with onset in adulthood (p<0.01). This difference was not statistically significant when adult heights were corrected for parental height. Also, height standard deviation scores for those patients with onset of disease before puberty were significantly lower than those with onset of disease during puberty (p<0.05) but after correction for parental height the difference was not significant. The site of disease had no influence on adult height. Patients who had used corticosteroids during puberty were significantly shorter than patients who had not (p=0.005). This was also true when corrected for target height (p=0.007). Conclusions: Although there was a trend indicating a deficit in adult height in patients with an early onset of Crohn's disease, once adjustment was made for parental height, this difference was not significant. Use of corticosteroids in puberty resulted in lower adult height.