AVES YAYINCILIK A.Ş. Acta Medica Okayama 2980-1478 50 5 2025 A Systematic Review and Meta-Analysis of Penis Length and Circumference According to WHO Regions: Who has the Biggest One? 291 301 EN Hadi Mostafaei Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Keiichiro Mori Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Satoshi Katayama Department of Urology Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Fahad Quhal Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Benjamin Pradere Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Takafumi Yanagisawa Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Ekaterina Laukhtina Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Frederik König Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Reza Sari Motlagh Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Pawel Rajwa Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Hanieh Salehi-Pourmehr Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Sakineh Hajebrahimi Department of Urology, Comprehensive Cancer Center, Medical University of Vienna Shahrokh F. Shariat Department of Urology, Comprehensive Cancer Center, Medical University of Vienna This study aimed to perform a systematic review and meta-analysis of stretched, erect, and flaccid penis length as well as circumference according to geographic WHO regions. PubMed, Embase, Scopus, and Cochrane Library were searched for articles published until February 2024. Studies in which a healthcare professional evaluated the penis size were considered eligible. After assessing the risk of bias, a systematic review and meta-analyses were performed according to the Preferred Reporting Items for Systematic Review and Meta-analysis statement, and the outcomes were grouped based on the WHO regions. A total of 33 studies comprising 36 883 patients were included. The risk of bias in the included studies was moderate/low. A comprehensive systematic review was done and meta-analyses performed for flaccid length [n = 28 201, mean (SE) 9.22 (0.24) cm], stretched length [n = 20 814, mean (SE) 12.84 (0.32) cm], erect length [n = 5669, mean (SE) 13.84 (0.94) cm], flaccid circumference [n = 30 117, mean (SE) 9.10 (0.12) cm], and erect circumference [n = 5168, mean (SE) 11.91 (0.18) cm]. The mean length of the stretched penis was largest in Americans [14.47 (0.90) cm]. The mean length of the flaccid penis was the largest in the Americas [10.98 (0.064) cm]. The mean flaccid penile circumference was largest in Americans [n = 29 714, mean (SE) 10.00 (0.04) cm]. Penis sizes vary across WHO regions, suggesting the need to adjust standards according to geography to better understand councilmen and their partners. These data provide a framework for discussing body image expectations and therapeutic strategies in this sensitive and emotional subject matter. No potential conflict of interest relevant to this article was reported.