A series of 14 children with Crohn's disease and growth retardation was screened for endocrine dysfunction. Four children presented with growth failure. All had normal cortisol responses to insulin-induced hypoglycaemia. Ten children had normal growth hormone responses in the same test, while four had abnormal responses. Gonadotrophin responsiveness to luteinizing hormone releasing hormone (LHRH) paralleled the clinical evidence of puberty, or its lack. Serum total thyroxine was normal in every patient, while serum total triiodothyronine was low in six; in these six patients serum triiodothyronine normalised with treatment. Serum folate was subnormal in 13 patients and the erythrocyte sedimentation rate was elevated in all at the time of diagnosis. Our results demonstrate a spectrum of endocrine changes seen in children with Crohn's disease, particularly prepubertal gonadotrophin responses to LHRH and a relative preservation of growth hormone and cortisol responsiveness to hypoglycaemia, with a defect in thyroxine to triiodothyronine conversion in severely ill children. Serum folate and sedimentation rate may be useful screening tests for Crohn's disease in a child presenting with failure of growth.