We evaluated the associations between clinical pharmacy services and mortality rates in 1029 United States hospitals. A data base was constructed from Medicare mortality rates from the Health Care Financing Administration and the National Clinical Pharmacy Services data base. A multivariate regression analysis, controlling for severity of illness, was employed to determine the associations. Four clinical pharmacy services were associated with lower mortality rates: clinical research (p<0.0001), drug information (p=0.043), drug admission histories (p=0.005), and participation on a cardiopulmonary resuscitation (CPR) team (p=0.039). The actual number of deaths (lower) associated with the presence of these four services were clinical research 21,125 deaths in 108 hospitals, drug information 10,463 deaths in 237 hospitals, drug admission histories 3843 deaths in 30 hospitals, and CPR team participation 5047 deaths in 282 hospitals. This is the first study to indicate that both centrally based and patient-specific clinical pharmacy services are associated with reduced hospital mortality rates. This suggests that these services save a significant number of lives in our nation's hospitals.