Adults with inflammatory bowel disease from North Carolina were questioned during 1986 and 1987 to assess risk due to a variety of childhood infections and treatments with antibiotics. Responses were compared with those of neighbor controls. Persons with Crohn's disease were more likely to report an increased frequency of childhood infections in general (odds ratio 4.67, 95% CI 2.65-8.23) and pharyngitis specifically (odds ratio 2.14, 95% CI 1.30-3.51). This was validated by an increased frequency of tonsillectomy (odds ratio 1.53, 95% CI 1.07-2.20). Crohn's cases were more likely to report frequent treatment with antibiotics for both otitis (odds ratio 2.07, 95% CI 1.03-4.14) and pharyngitis (odds ratio 2.14, 95% CI 1.20-3.84). Although Crohn's cases were more likely to report frequent exposure to penicillin (odds ratio 1.81, 95% CI 0.98-3.31), there did not appear to be excess risk conferred by penicillin after controlling for frequency of infections. Persons with ulcerative colitis also reported an excess of infections generally (odds ratio 2.37, 95% CI 1.19-4.71), but not an excess of specific infections or treatments with antibiotics. Persons who reported an increased frequency of infections tended to have an earlier onset of Crohn's disease (P < 0.0001) and ulcerative colitis (P = 0.04). Finally, it was noted that urban living in childhood increased the risk for Crohn's disease. We conclude that childhood infections may be a risk factor for Crohn's disease and may presage the early onset of disease.