Background: Second generation androgen receptor inhibitors (SGARIs), apalutamide (APA) and enzalutamide (ENZ) and darolutamide, are approved in the United States (US) for the treatment of nmCRPC. The objectives of this study were to describe the frequency of AEs and actions taken to manage AEs among nmCRPC patients treated with APA or ENZ and their downstream resource implications. Methods: This is a further descriptive analysis of a retrospective chart review study conducted in 43 US nmCRPC-treating sites. In our sample, the 43 physicians identified 699 nmCRPC patients initiating treatment with APA (N = 368) or ENZ (N = 333) with 2 patients receiving both, between February 1, 2018 and December 31, 2018 and AEs were collected as reported in regular clinical practice. A representative subset of patients, experiencing at least 1 AE for either APA (N = 125) or ENZ (N = 125), were selected randomly from the initial cohort, and their detailed chart data were extracted to understand the actions taken to manage AEs. Results: Of the initial cohort of nmCRPC patients, 72.0% and 78.7% of men receiving APA (N = 368) and ENZ (N = 333) experienced ≥1 AE, respectively. The three most common AEs reported were fatigue/asthenia (APA, 30.2%; ENZ, 38.7%), hot flush (APA, 14.1%; ENZ, 13.5%), and arthralgia (APA, 14.4%; ENZ, 12.9%). Cognitive and mental changes were observed in 5.4% (APA) and 7.8% (ENZA) men. The subset analysis of randomly selected patients experiencing ≥1 AE (APA, 125; ENZ, 125) were mostly Caucasian (APA, 72.8%; ENZ, 71.2%), ECOG score 0-1 (APA, 84%; ENZ, 88%), median prostate specific antigen (PSA) value 13 ng/ml and 11 ng/ml (APA, ENZ; respectively). Actions to address AEs included treatment of AE, SGARI discontinuation, dose reduction and hospitalization (Table). Specifically, treatment discontinuation due to AE was observed in 8.0% (APA) and 12.8 (%) of men. AEs were often not resolved (APA, 43.6%; ENZ, 39.4%), and the median duration of days to resolve AEs were 60.0 for APA and 56.0 for ENZ. Conclusions: This real-world study highlights the clinical and resource use burden of AEs among nmCRPC patients treated with APA and ENZ. The results demonstrate the importance of safety and tolerability as key considerations in shared clinician-patient decision-making regarding SGARI therapy in nmCRPC.