During a 2.5-yr follow-up of 263 opioid addicts, suicidality was examined as a predictor of outcome and as an outcome to be predicted among initially nonsuicidal addicts. Suicidality predicted poor medical, psychosocial, and substance abuse outcomes, but fewer legal problems during follow-up. Among the 218 initially nonsuicidal opioid addicts, subsequent suicidality was not associated with a history of drug overdoses, and psychosocial factors predictive of future suicidality differed from factors associated with a history of overdoses. Factors associated with overdoses included alcoholism, poor social adjustment, and legal problems, while depression, neuroticism, and family problems predicted suicidality during the subsequent 2.5 yr.