Heroin users are at high risk for suicide. However, the epidemiological profile of suicidal behaviors in Chinese methadone-maintained patients remains largely unknown. This study determined the prevalence and correlates of suicidal ideation among Chinese methadone-maintained patients. A total of 603 methadone-maintained patients were consecutively recruited from three methadone maintenance treatment (MMT) clinics in Wuhan, China, and administered with standardized questionnaires to collect sociodemographic, clinical, and psychological data. Suicidal ideation was measured with a single self-report question "Have you ever thought about committing suicide?". Depression and anxiety were assessed with Zung's Self-rating Depression Scale and Zung's Self-rating Anxiety Scale, respectively. The one-month and lifetime prevalence rates of suicidal ideation were 17.9% and 58.9%, respectively. In multiple logistic regression, lifetime suicidal ideation was significantly associated with female (OR: 1.69), an educational attainment of primary school and below (OR: 1.47), fair and poor interpersonal relationship (OR: 2.20), a history of injecting heroin (OR: 1.60), depression (OR: 1.38), and anxiety (OR: 4.00). Methadone-maintained patients of MMT clinics have a high prevalence of suicidal ideation and therefore at high risk for suicide. Suicide prevention efforts at MMT clinics should include periodic evaluation of suicidality, psychosocial supports, and, when necessary, psychiatric treatment and crisis intervention.