Relationships among attempted suicide, nonsuicidal self-harm, and physical assault were examined in 400 regular users of heroin and/or psychostimulants. Twenty-eight percent had episodes of nonsuicidal self-harm, 32% had attempted suicide, and 95% had been violently assaulted. The number of suicide attempts and nonsuicidal self-harm incidents were correlated (rho = 0.44). There were also significant correlations between the number of assaults and nonsuicidal self-harm incidents (rho = 0.17), and suicide attempts (rho = 0.27). The mean age onset for non-suicidal self-harm (18.9 yrs) was significantly younger than that of initial suicide (22.3 yrs). The age at initial physical assault (16.0 yrs) was significantly younger than that of nonsuicidal self-harm and initial suicide attempt. Screening for all forms of violence appears warranted when determining suicide risk for this population. (Contains 1 table and 1 figure.)