Hospitals must balance costs associated with pharmacist medication reconciliation (e.g., salary) with prevented harm and cost avoidance (e.g., unreimbursed expenses resulting from medication error). This study found an estimate cost avoidance of $47,000 - $231,000 during one month in one hospital. The highest-risk, highest-cost classes were insulin, antithrombotics, and opioids. In resource-limited environments, focusing on the highest-cost classes could avoid significant cost and patient harm.