In order to determine patterns and correlates of attempted suicide amongst heroin users across 3 years, a cohort of 387 heroin users (134 entering maintenance treatment, 134 entering detoxification, 81 entering residential rehabilitation and 38 not entering treatment) were interviewed about suicide attempts at baseline, 12, 24 and 36 months. Across the follow-up period, 11.6% attempted suicide. There were declines in the proportion who attempted suicide each year amongst both males and females and significant declines in Major Depression, suicidal ideation and current suicide plans. Despite this, levels of attempted suicide, suicidal ideation and Major Depression in the cohort remained higher than in the general population. Those who had made a previous suicide attempt were five times more likely to make an attempt across follow-up and there was a strong association between an attempt in any 1 year and increased probability of an attempt in the subsequent year. A quarter of those who reported suicidal ideation at baseline made an attempt across follow-up. At each interview point, current suicidal ideation was strongly associated with increased risk of a suicide attempt in the following year. Independent predictors of a suicide attempt across follow-up were a lifetime suicide history, baseline suicidal ideation, social isolation and the extent of baseline polydrug use. Given the strong predictive value of suicidal ideation and previous attempts, regular brief screening would appear warranted to identify those at greatest risk.