Objective: The primary purpose of this research was to compare the service use of patients diagnosed with alcohol dependence to the service use of patients diagnosed with other chronic illnesses. The secondary purpose was to determine the impact of comorbid alcoholism on the service use of patients with chronic illnesses. Methods: The sample included 67,878 veterans diagnosed with alcohol dependence, depression, or diabetes who were treated by the Department of Veterans Affairs in 1993. The number of inpatient days and outpatient visits over a 4-year period (1991 to 1995) were compared using regression models to control for differences in casemix. Results: Controlling for casemix, patients treated for alcohol dependence had significantly fewer outpatient visits than patients treated for either depression or diabetes. Patients treated for alcohol dependence also had significantly fewer inpatient days than patients treated for depression, but significantly more inpatient days than patients treated for diabetes. Comorbid alcoholism was prevalent among patients treated for depression and diabetes. Comorbid alcoholism increased the number of inpatient days for patients treated for depression or diabetes and increased the number outpatient visits for patients with depression. However, comorbid alcoholism decreased the number of outpatient visits for patients treated for diabetes. Conclusions: Results suggest that patients with alcohol use disorders should not be singled out as being more costly to treat than patients with other chronic illnesses. These findings are in stark contrast to those from studies comparing individuals with alcohol use disorders to relatively healthy individuals sampled from at-risk populations. Key Words: Alcoholism, Comorbidity, Service Utilization.