BACKGROUND: Professional basketball players in the National Basketball Association (NBA) subject their lower extremities to significant repetitive loading during both regular-season and off-season training. Little is known about the incidence of lower extremity bony stress injuries and their impact on return to play and performance in these athletes. HYPOTHESIS: Stress injuries of the lower extremity will have significant impact on performance. STUDY DESIGN: Case series. LEVEL OF EVIDENCE: Level 4. METHODS: All bony stress injuries from 2005 to 2015 were identified from the NBA. Number of games missed due to injury and performance statistics were collected from 2 years prior to injury to 2 years after the injury. A linear regression analysis was performed to determine the impact of injury for players who returned to sport. RESULTS: A total of 76 lower extremity bony stress injuries involving 75 NBA players (mean age, 25.4 +/- 4.1 years) were identified. Fifty-five percent (42/76) involved the foot, and most injuries occurred during the regular season (82.9%, 63/76), with half occurring within the first 6 weeks. Among players who sustained a fifth metatarsal stress fracture, 42.9% were unable to return to professional play. Players who sustained stress injuries had reduced play performance, specifically related to number of games played ( P = 0.014) and number of steals per game ( P = 0.004). Players who had surgery had significantly better performance at 2 years than those who were managed nonoperatively, independent of the type of injury (beta = 4.561; 95% CI, 1.255-7.868). CONCLUSION: Lower extremity bony stress injuries may significantly affect both short- and long-term player performance and career length. Stress injuries result in decreased player performance, and surgical intervention results in improved performance metrics compared with those treated using conservative methods. CLINICAL RELEVANCE: Stress injuries result in decreased player performance, and surgical intervention results in improved performance metrics.