Sexual victimization of adult women remains an underreported crime. This systematic review identified and synthesized the barriers to reporting, investigating, prosecuting, and sentencing cases of sexual assault and rape against adult women in Western countries. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a comprehensive search was conducted on August 3, 2023, across databases including PsycINFO, MEDLINE, Cochrane Library, Scopus, ProQuest Central, Web of Science, MedNar, and ProQuest Dissertations & Theses. Studies meeting the inclusion criteria provided relevant information on the decision not to formally disclose, investigate, prosecute, or convict incidents of sexual assault and rape of adult women. We included 28 studies and identified 70 barriers in total. Identified barriers were most prevalent to reporting, followed by investigating, prosecuting, and, lastly, sentencing. Key themes in the barriers included lack of trust in the criminal justice system, internal reactions, rape myths and societal norms, and perpetrator characteristics. The identified barriers emphasize an urgent need for reform of the criminal justice system's response to sexual assault and rape. Prioritizing victim-survivors' needs, enhancing transparency of the criminal justice system, and addressing attrition rates are crucial. Future studies need to engage with diverse population to address all victim-survivors' needs and provide further insights into the challenges across all stages of the criminal justice system to enhance the outcome of rape and sexual assault cases. [ABSTRACT FROM AUTHOR]