Introduction: Little is known about the specific characteristics of suicidal behaviour in people receiving treatment for substance use disorder (SUD). Purpose: The aim of this study was to describe the number and type of suicide attempts and the methods used by patients with SUD from a gender perspective. Method: A total of 215 patients (177 men and 38 women) were interviewed about their lifetime suicidal behaviour using the Columbia-Suicide Severity Rating Scale. Results: Of the total sample, 48.8% (n = 105) of the patients reported having suicidal ideation, and 28.8% (n = 62) reported attempting suicide in addition to having suicidal ideation. The most common type of suicide attempt was actual suicide attempts (20.5%; n = 44), followed by aborted suicide attempts (6.0%; n = 13) and interrupted suicide attempts (2.3%; n = 5). Women had more aborted attempts than men did (13.2% vs. 4.5%; X2= 4.11; d.f. = 1; p = .043). The most common method of suicide was overdose (51.6%; n = 32), followed by jumping from a height (17.7%; n = 11). Regarding the number of suicide attempts, most of the participants who attempted suicide (n = 62) made only one attempt (n = 30; 48.4%). Conclusions: The projection of these figures is alarming. These results justify the need to integrate suicide prevention interventions into addiction treatment programmes.