Background: Worldwide statistics highlight that many adolescents suffer from various types of maltreatment, which often tend to co-occur in the form of poly-victimisation. The experience of maltreatment at a young age causes physical and mental health problems, and can also lead to self-harm and suicide.The aim: To explore the possible impact of maltreatment and polyvictimisation on adolescent self-harm and suicide attempts. Participants and settings: In total, 1898 students (15-18 years old) from Lithuanian vocational schools completed the survey (65.5% male). Method: The impact of maltreatment and poly-victimisation on self-harm and suicide attempts was tested using multivariable binary logistic regressions. Results: Different maltreatment types were significantly associated to selfharm (odds ratio from 2.47 to 3.80, p < 0.001) and suicide attempts (odds ratio from 3.15 to 7.58, p < 0.001). The odds ratios for self-harm and suicide attempt increased as the number of different types of maltreatment experienced increased. A history of experiencing four types of poly-victimisation increased adolescent risk for self-harm (OR = 18.57, p < 0.001, 95% CI: 5.77-59.72) and suicide attempts (OR = 45.54, p < 0.001, 95% CI: 14.37-144.28) the most. Conclusion: Adolescents with experience of maltreatment, particularly if polyvictimised, are at greater risk of engaging in self-harming and suicidal behaviours.adolescents, maltreatment, poly-victimisation, self-harm, suicide attempts Key Practitioner Messages • Adolescents with experience of maltreatment are more likely to engage in self-harm or suicidal behaviours compared to non-victimised peers. • Sexual abuse is associated with the greatest probability of suicide attempt compared to other forms of maltreatment. • The risk of self-directed violence increases as the number of maltreatment types experienced increases.