Objectives: Nonoperative management vs. early reconstruction for partial tears of the medial ulnar collateral ligament (MUCL) remains controversial, with the most common treatment options for partial tears consisting of rest, rehab, platelet rich plasma (PRP), and/or surgical intervention. However, whether the improved outcomes reported for treatments such as MUCL reconstruction (UCLR) or nonoperative management with a series of PRP injections justifies their increased upfront costs remains unknown. Thus, the purpose of this study was to compare the cost-effectiveness of an initial trial of physical therapy alone, an initial trial of physical therapy plus a series of PRP injections, and early UCLR to determine the preferred cost-effective treatment strategy for baseball pitchers with partial tears of the MUCL. Methods: A Markov Chain Monte Carlo probabilistic model was developed to evaluate the outcomes and costs of 1,000 simulated pitchers undergoing nonoperative management with and without PRP vs. early UCLR for partial MUCL tears. Utility values, RTP rates, and transition probabilities were derived from the published literature. Costs were determined based on the typical patient undergoing each treatment strategy at our institution. Outcome measures included costs, acquired playing-years (PYs), and the incremental cost-effectiveness ratio (ICER). Results: Mean total costs resulting from nonoperative management without PRP, nonoperative management with PRP, and early UCLR were $22,520, $24,800, and $43,992, respectively. On average, early UCLR produced an additional 4.0 PYs over the 10-year time horizon relative to nonoperative management, resulting in an ICER of $5,395/PY, which falls well below the $50,000 willingness-to-pay threshold (WTP). Overall, early UCLR was determined the preferred cost-effective strategy in 77.5% of pitchers included in the microsimulation model, with nonoperative management with PRP determined the preferred strategy in 15% of pitchers and nonoperative management alone in 7.5% of pitchers. Conclusions: Based on Monte Carlo microsimulation and probabilistic sensitivity analysis, early UCLR was demonstrated to be more cost-effective than an initial trial of nonoperative management for partial tears of the MUCL for the majority of high-level baseball pitchers. It is important to note that this model does not consider the unique experiences, goals, situations, career trajectory, and pitching horizons of individual patients, and thus a shared decision-making discussion should be conducted regarding optimal initial treatment for partial MUCL tears. This is particularly true as many athletes can successfully be treated non-operatively, which generally results in a quicker return to play when successful compared to surgery.