BACKGROUND: Comorbidity is common in elderly persons. Its extent,correlates, and life-threatening impact in representative communityresidents are unclear. METHODS: Self-reported information of physician-diagnosed coronary artery disease (CAD), cerebrovascular disease (CVD),diabetes, and cancer was obtained annually between 1986-87 and 1992-93, andhypertension was obtained triennially from the participants of the DukeEstablished Populations for Epidemiologic Studies of the Elderly, astratified multistage sample of 4,126 Black and White community residentsaged 65-100, living in a five-county area of North Carolina. Date of deathwas obtained from death certificates identified through search of theNational Death Index. Statistical procedures included descriptivestatistics, logistic regression, and survival analysis. RESULTS: Of thissample, 57% reported hypertension, 20% diabetes, 15% CAD, 9% cancer, and 9%CVD; 29% reported none of these conditions, whereas 29% reported two ormore. Demographic characteristics were not related to comorbidity with CVDor cancer. Increased education tended to be protective. The effect of age,gender, and race varied with condition. At baseline there was substantialcomorbidity among hypertension, CAD, CVD, and diabetes, but not withcancer. Hypertension, CVD, and diabetes were risk factors for CAD, whereasdiabetes was a risk factor for CVD. After controlling for demographiccharacteristics, all health conditions except hypertension were predictiveof 6-year mortality, as was the presence of comorbidity. CONCLUSION: Wefound significant comorbidity in older persons who have hypertension, CAD,CVD, or diabetes; particular risk of developing comorbidity, particularlyCAD, among those with hypertension, CVD, and diabetes; and risk of CVD inthose with diabetes. With the exception of hypertension, these conditions,and comorbidity per se, are life- threatening.