This study evaluated the severity of illness of patients experiencing inpatient hospital complications in two hospitals in the metropolitan area of Syracuse, New York. It involved identification of inpatient complications by All Patients Refined (APR) severity of illness for pneumonia, clostridium difficile colitis, and urinary tract infection. Severity of illness was identified for each patient at the time of admission. The study showed that patients at the two highest levels of severity of illness, Major and Extreme, accounted for 76-93 percent of those with the three complications evaluated. These patients comprised less than 40 percent of the inpatient populations of the hospitals. At the same time, the study showed that only 0-23 percent of patients at Minor or Moderate severity of illness experienced inpatient complications. These low severity of illness categories accounted for 60 percent or more of inpatients in the Syracuse hospitals. Results of the study suggested that efforts to reduce hospital inpatient complications could focus on those patients with high severity of illness. They also suggested that these efforts could largely avoid patients with low severity of illness and, as a result, save clinical and quality assurance resources in hospitals.