It has been reported that some natural catastrophes increase morbidity rates for illness. In this study, we investigated the impact of the 1995 Hanshin-Awaji earthquake on morbidity rates for various illnesses by analysis for correlations between the extent of damage due to the earthquake and occurrences of various illnesses. We searched the medical records of 1948 patients hospitalized due to illness in 48 hospitals during the first 15 days after the earthquake. In each of 14 affected areas, the hospital admission rate and estimated morbidity ratio for each illness were calculated. Destruction ratios were determined based upon the number of dwellings completely destroyed in each area. For total illnesses and each major illness, linear regression analyses were performed comparing hospital admission rates, estimated morbidity ratios, and destruction ratios. Hospital admission rates and estimated morbidity ratios among the 1948 patients were significantly correlated to destruction ratios. With pneumonia, dehydration, acute heart failure, asthmatic attack, and peptic ulcer, hospital admission rates and estimated morbidity ratios were significantly related to destruction ratios, while no significant correlations between estimated morbidity ratios and destruction ratios existed for cerebral vascular disease or ischemic heart disease. Peptic ulcer and pneumonia showed especially high correlation values (age- and sex-adjusted R2>0.7). The present study revealed a strong link between the extent of damage due to the catastrophic earthquake and an increase in morbidity rates for acute illnesses, especially peptic ulcer and pneumonia.