Background:With widespread medication choices for metastatic castration-resistant prostate cancer (mCRPC) is now available, on the other hand biomarker to predict the efficacy of each mCRPC treatment has not been established.Objective:This study developed prognostic nomogram to predict prognosis in CRPC patients who received abiraterone acetate (ABI) and/or enzalutamide (ENZ).Design, Setting, and Participants:A total of 568 mCRPC patients received ABI and/or ENZ from 2012 to 2017 were enrolled in this study. We developed prognostic nomogram based on the risk factors by Cox proportional hazards regression model.Outcome Measurements and Statistical Analysis:The nomogram was also assessed for discriminatory ability with the concordance index (C-index). We repeated 5-fold cross-validation 2000 times to estimate the C-index and reported the means of the estimated C-index for the training and validation sets. And we also developed nomogram application software (app) based on this nomogram.Results and Limitations:The median overall survival (OS) was 24.7 months. A multivariable analysis showed that the time to CRPC, pre-chemotherapy, baseline PSA, baseline ALP, and baseline LDH were independent risk factors for the OS (HR: 0.521, 1.681, 1.439, 1.827, 12,123, p:0.001, 0.001, <0.001, 0.019, <0.001)). C-index was 0.72 in training cohort and 0.71 in validation cohort.Conclusion:We developed nomograms to predict the OS for Japanese mCRPC patients who received ABI and/or ENZ. The advent of mCRPC prognosis prediction app will facilitate greater accessibility for clinical use.Patient SummaryThis study developed and validated a nomogram for predicting the prognosis of mCRPC patients who receive ABI/ENZ treatment using clinical information. This study also developed mobile app to facilitate clinical usage.