Background and Objective: The anti-neoplastic activities of metformin were investigated in many pre-clinical and clinical studies. In this study, metformin which is familiar oral drug, cheap and available in all places was used to evaluate its efficacy in Egyptian patients with advanced prostate cancer. Materials and Methods: Twenty six patients with advanced prostate cancer either treatment naïve or previously treated were subjected to metformin therapy. Metformin was administered as glucophage1000 mg twice daily concomitantly with standard of care treatment continuously till disease progression, drug toxicity or patient refusal. Results: The median age of studied patients was 65 years, range 59-75 with median body mass index 24.75 range 17-40, 18 cases had ECOG PS of one and the remaining cases were ECOG 2. Out of 26 patients, 17 were treatment naïve while 9 of them were subjected to previous SOC treatment. The overall response (CR, PR) was 53.8%, no response (SD, PD) represented 46.2% and the median time to tumor progression (TTP) was 18 weeks but it was significantly different in previously treated cases and treatment naive cases, in which median TTP in previously treated case was 8 weeks compared to 32 weeks in treatment naïve cases [p , HR (95%CI) 12.326 (3.212-47.306)]. Conclusion: Metformin was well tolerated and had encouraging results for patients with advanced prostate cancer.