Background Birth parents of children in the statutory child protection system have disproportionally high rates of trauma exposure and mental health problems, however, little is known about the extent to which this population display symptoms of Post-Traumatic Stress Disorder (PTSD) or Complex PTSD. This study provides a systematic review and meta-analysis of the PTSD rates in parent samples involved in the child protection services. Method Articles were identified by searching PSYCINFO, Medline, CINAHL, and PILOTS. The search included terminology pertaining to parents, trauma, and child protective services and we included all peer-reviewed articles that reported a valid measure of PTSD and child protection service involvement. Results Fifteen studies were included in the review with a combined prevalence estimate for PTSD based on 11 studies ( n = 4871) was 26.0% (95% CI 20.0–32.0%) for mothers, and estimate based on three studies ( n = 2606) was 13.0% (95% CI 7.0%–18.0%) for fathers and 23.0% (95% CI 17.0–29.0) for all parents based on 7848 responses. Four studies that did not report prevalence rates, reported sample mean scores for PTSD that were consistently higher than in general population. Factors associated with parents’ PTSD symptoms included mental health co-morbidities, victimization of physical and sexual violence, and perpetration of child abuse. Conclusion There are high rates of PTSD in parents involved in the protective system, thus more targeted efforts are needed to identify and adequately address trauma symptoms of parents as part of child protection interventions.