Background: Sexual assault (SA) can induce a negative impact on victims' mental health. Specialised SA services generally offer medical care and a forensic examination to SA victims. However, there is a large variation in how these services provide mental health support.Objective: This study aims to assess mental health problems of SA victims attending the Belgian Sexual Assault Care Centres (SACCs) and identify predictors for victims' use of support from in-house psychologists.Method: Health records of victims >= 16 years who presented within one week post-SA to one of the three Belgian SACCs between 25 October 2017 and 31 October 2019 were reviewed. An AIC-based stepwise backward binary logistic regression was used to analyse the association between victim, assault, service use and mental health characteristics and follow-up by a SACC-psychologist.Results: Of the 555 victims, more than half had a history of mental health problems. Of those assessed, over 70% showed symptoms of posttraumatic stress disorder (PTSD), depression and/or anxiety disorder. One in two victims consulted a SACC-psychologist. Victims with a mental health history (OR 1.46, p = .04), victims accompanied by a support person during acute care (OR 1.51, p = .04), and victims who were assaulted by an acquaintance in comparison to those assaulted by a stranger (OR 1.60, p = .039) were more likely to attend their appointment with the SACC-psychologist.Conclusion: The study reaffirms the high mental health burden among victims attending specialised SA services, stressing the need to provide effective mental health interventions at these services and improve their longer-term use by victims. Prescheduling of appointments with an in-house psychologist in combination with phone reminders may improve the uptake of such services. Health care providers must be vigilant about potential barriers faced by victims without a mental health history or social support in attending appointments with mental health professionals.