Primary care providers (PCPs) provide the majority of care patients receive during their lifetime. We consider the problem of determining the size and composition of physician panels in primary care. A physician’s panel consists of a set of patients and each patient belongs to one of many different health-related categories. Using real data collected at the Mayo Clinic at Rochester, we propose a multi-period metaheuristic simulation optimization model for determining the panel design of a set of physicians working in a primary care environment. The model seeks to maximize patient visits to their own providers, reduce waiting times, and minimize overage.