This study is attempting to determine if family members (parents, siblings, offspring, and spouses) of newly hospitalized cases of ulcerative colitis and proctitis, regional enteritis, and Crohn's disease of the colon have greater prevalence of these diseases than family members of controls. Newly hospitalized cases are being ascertained through a case register in Baltimore and from local hospitals. Medical records of cases are being abstracted; and reviewed by a gastroenterologist. Cases and family members will be interviewed regarding previous illnesses; tobacco, alcohol, and dietary habits; and demographic characteristics. Information will be obtained concerning all family members, living and dead. Hospital controls will be matched by sex, color, and age to each case. Hospital controls and their family members will be interviewed in the same manner as cases, and medical records will be obtained. Neighborhood controls will be matched to cases by sex, color, and age. These controls and their family members will be interviewed in the same manner as cases, and medical records will be obtained. Death certificates will be obtained for all cases and family members who have died. Serum will be collected from cases, controls, and family members, and will be frozen at -70 degrees centigrade for future studies.