Background: The mortality risk is high among individuals dependent on heroin, and suicide is a severe consequence of long-term heroin use. We estimated the incidence of suicide mortality and its risk factors in a large Asian cohort with heroin dependence. Methods: A consecutive series of 2750 inpatients dependent on heroin admitted to a psychiatric center in northern Taiwan between 1990 and 2010 were retrospectively enrolled as the study cohort. These patients were linked to the Taiwan National Mortality Database to obtain each mortality event. We determined the Standardized Mortality Ratio (SMR) for each cause of death. Among the deceased, 69 deaths were due to suicide (cases); 138 controls were randomly selected using risk-set density sampling based on a nested case-control design. We collected clinical information from subjects' medical records. Multivariate conditional logistic regression was employed to explore the correlates of suicide mortality. Results: The findings showed a 7.9-fold SMR for all-cause mortality among heroin users compared to the general population while the SMR for suicide mortality was 16.2. Multivariate analysis showed that suicide attempt as the reason for the index admission (adjusted risk ratio [RR] = 4.29, p= 0.035) and depressive syndrome anytime during life (adjusted RR = 2.61, p= 0.019) were associated with the risk of suicide mortality. Conclusions: Individuals dependent on heroin are more likely to die of suicide compared to the general population. We recommend that clinical psychiatric staff carefully gather information related to the identified risk factors to prevent suicide among heroin users.