The goal of this study was to determine the contribution of substance abuse to the expression of suicidal ideation in a sample of patients referred for evaluation of chemical dependency in a large urban Psychiatric Emergency Service (PES). Records from 777 consecutive patients referred to the chemical dependency service of the PES were analyzed. Of this sample, 43.7% of the patients with only a cocaine use disorder expressed suicidal ideation compared to 38% of those with both cocaine and alcohol use disorders, 24.3% with only an alcohol use disorder and 17% with other drug use disorders (chi(2)=24.768; df=3; P<0.0001). More than half of the patients (55.26%) with a substance-induced mood or psychotic disorder expressed suicidal ideation (chi(2)=23.174, df=1, P<0.0001), and the majority (85%) of these patients had a cocaine use disorder (chi(2)=12.309, df=1, P<0.0005). In this sample of patients served by an urban PES, cocaine use is associated with suicidal ideation, more so than other substances of abuse.