28 Background: The impact of daily oral prednisone (P) on toxicities and outcomes in men with metastatic castration-resistant prostate cancer (mCRPC) is unclear. We conducted a meta-analysis of randomized trials comparing regimens that included P in only one arm. Methods: PubMed, conferences and clinicaltrials.gov databases were searched for articles reported from January 1966 to June 2013. Eligible studies were selected in an unbiased manner and limited to randomized trials enrolling patients with mCRPC and comparing regimens administering P in only one arm. Data extraction was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Arms containing P were compared with arms without P for severe toxicities grade 3 or higher and overall survival (OS). Results: Five randomized trials were published or presented with P in only one arm: by Scher and colleagues comparing docetaxel (D) plus P versus D plus DN101 (n=953), by Higano and colleagues comparing DP versus GVAX (n=621), by Small and colleagues comparing DP versus GVAX plus D (n=394), by Fossa and colleagues comparing P versus flutamide (n=201) and by Petrylak and colleagues comparing mitoxantrone plus P versus D plus estramustine phosphate (n=770). The total number of patients was 2,939, of whom 1,471 received therapy not containing P and 1,468 received therapy containing P. All five trials were eligible for analysis of toxicities, but the Fossa trial was excluded for the OS analysis due to lack of required parameters. There was no difference between the non-P and P groups for severe toxicities (incidence rate ratio [IRR] = 0.82, p = 0.712, I2 = 97.9%). When examining toxicities as a reason for discontinuing therapy, the non-P groups were not different from the P groups (relative risk [RR] = 1.24, p = 0.413, I2 = 86.8%). The non-P groups demonstrated no difference in OS compared to the P groups (HR = 1.09, p = 0.531, I2= 79.7%). The meta-analysis is limited by the trial level design and small number of patients and does not exclude a favorable palliative impact of P. Conclusions: This meta-analysis of randomized trials in mCRPC suggests no significant impact on severe toxicities and OS with the use of daily oral prednisone.