Based on a model previously used to estimate health care costs of drug-related problems, this study measured the economic impact of providing pharmaceutical care to an ambulatory patient population. The authors used a probability pathway model and the input of a selected expert panel of pharmacists to determine the effects of pharmaceutical care on cost savings. They concluded that with the reductions in negative therapeutic outcomes, pharmaceutical care can avoid more than $45 billion in direct health care costs. Using this study and their previous research, the authors support the growth of active pharmacy involvement in improving patient care and coordination.