Sickness was observed among cases of chronic disease in 1234 families residing in selected blocks of Baltimore. Illness rates among the chronic-disease sufferers (not counting the chronic illness) were 77% higher among the [male][male] and 40% higher among [female][female] than in the rest of the population. Approx. 1/4 of the total days of disability occurred among the 80% of the population who had no chronic illness, a similar amt. was found among the 2% non-ambulatory chronic disease sufferers and 1/2 the disability was found among the remaining 18% ambulatory persons with chronic diseases. 25% of all families in the survey had 1 or more cases of chronic disease.