Objective: Sexual assault peaks in adolescence, yet sequelae at this age are not well understood. This systematic review aimed to describe mental health outcomes following sexual assault in young people. Method: Two reviewers independently searched databases, screening publications from 1990 to 2018. Inclusion criteria included: longitudinal studies, systematic reviews, and meta-analyses with ≥50% participants aged ten to 24 years; baseline mental health assessment prior to/or <8 weeks post-assault with follow-up ≥ 3 months after the initial assessment.Results: 5 124 titles and abstracts were screened, with 583 papers examined in full. Ten studies met inclusion criteria (sample size 31 to 191). Five studies examined rates of post-traumatic stress disorder (PTSD), reporting rates of up to 95% within one month and up to 60% at 12 months post-assault. Studies evaluating post-traumatic (n = 5) and anxiety (n = 3) symptom scores showed symptoms were highest in the immediate aftermath of the trauma, generally reducing over four to 12 months post-assault. Depressive symptomology appeared to vary between studies (n = 5). However, the majority showed symptoms decreasing over the same time period.Conclusions: Psychopathology is common following sexual assault in young people. Most studies observed reduced rates over time, but there is a paucity of longitudinal research. Psychopathology during the first year after sexual assault is an important treatment target to consider.