Background There is minimal work defining the economic impact of resident participation in shoulder arthroplasty. Thus, this study quantified the opportunity cost of resident participation in total shoulder arthroplasty (TSA) and hemiarthroplasty (HA) by determining differences in operative time, relative value units (RVUs)/hour, and RVUs/case. Methods A retrospective analysis of shoulder arthroplasty procedures were identified from the ACS-NSQIP database from 2006 to 2014 using CPT codes. Demographic, comorbidity, preoperative laboratory data and surgical procedure were used to develop matched cohorts. Mean differences in operative time, RVUs/case and RVUs/hour between attending-only (AO) cases and cases with resident involvement (RI) were examined. Cost analysis was performed to identify differences in RVUs generated per hour in dollars/case. Results A total of 1786 AO and 1102 RI cases were identified. With the exception of PGY-3 and PGY-4 cases, RI cases had lower mean operative times compared to AO cases. The cost of RI was highest for PGY-3 ($199.87 per case) and PGY-4 ($9 .2 9) residents with all other postgraduate years providing a cost reduction. Discussion Involvement of residents was associated with shorter operative times leading to a savings of $29.64 per case. Involvement of intermediate-level (PGY-3) residents were associated with increased costs that ultimately decreased as residents became more senior.