This study evaluated the economic impact of patient-focused pharmacist intervention in the community retail setting in patients with hypertension, diabetes, asthma, and/or hypercholesterolemia. Specially trained pharmacists intervened by providing targeted patient education, performing systematic patient monitoring, offering feedback and behavior modification, and communicating regularly with patients' physicians to enable early intervention for drug-related problems. We evaluated prescription drug costs and total medical costs by comparing claims data from 188 patients enrolled in the program at three intervention pharmacies with data from 401 control patients at five nonparticipating pharmacies from the same retail chain. For all disease states, the average cost per prescription was significantly higher in the group receiving intervention than in the control group. Differences in total monthly prescription costs were significant only for patients with asthma, with higher monthly costs in the group receiving intervention. Substantial savings were demonstrated across all cost analyses for total monthly medical costs. Savings ranged from a conservative estimate of $143.95 per patient per month to $293.39 per patient per month when accounting for the possible influence of age, comorbid conditions, and disease severity. Our data indicate that pharmacist intervention in this community pharmacy-based disease management model substantially reduced monthly health care costs in patients with hypertension, hypercholesterolemia, diabetes, and asthma.