OBJECTIVE: This study estimated the prevalence and correlates of self-harm among adult victims of human trafficking who accessed secondary mental health services, and it estimated the responses of mental health services to these individuals. METHODS: A clinical records database was searched for self-harm, sociodemographic, clinical, and service use characteristics among trafficked adults who accessed secondary mental health services in South London (2006-2012). Logistic regression models compared trafficked patients (N=84) and a matched cohort of nontrafficked patients (N=287). RESULTS: Among trafficked patients, 33% had engaged in self-harm prior to care and 25% in self-harm during care. After engaging in self-harm, trafficked patients were more likely than nontrafficked patients to be admitted as a psychiatric inpatient (adjusted odds ratio [AOR]=2.81) but less likely to visit an emergency department (AOR=.47). CONCLUSIONS: Self-harm is prevalent among trafficked adults accessing secondary mental health services, and mental health professionals have a crucial role to play in supporting survivors.