The increase in life expectancy that would result from the elimination of certain diseases and the resulting change in hospital utilization vary, depending on the disease. In some cases, life expectancy would rise and total days spent in hospital would decline, while in others, the gain in life expectancy would be accompanied by an increase in hospital days. For instance, if mental health disorders were eliminated, the increase in life expectancy at age 45 would be minimal: from 34.9 to 35.3 years, but time spent in hospital would decline from 168 to 151 days. By contrast, if diseases of the circulatory system were eliminated, life expectancy at age 45 would rise from 34.9 to 41.6 years, but time spent in hospital would also rise: from 168 to 209 days. Elimination of not only mental illnesses but also injuries and poisoning and diseases of the nervous system has the potential of both increasing life expectancy and reducing hospital use.