The objective of this study was to identify correlates of suicidal ideation and to examine the hypothesis that injection drug users (IDUs) were more likely to report suicidal ideation than noninjection drug users (NIDUs). Participants included IDUs (n = 244) and NIDUs (n = 73) from Baltimore, Maryland, aged 15-30 who began snorting or smoking heroin or cocaine/crack (NIDUs) or injecting drugs (IDUs) within the past 5 years who were recruited between August 2000 and March 2002. Among the 317 participants, 42% were female, 59% were white, and median age was 24. The prevalence of suicidal ideation was 27%. IDUs were more likely to report suicidal ideation than NIDUs (31% vs. 14%, p = 0.003). Adjusting for age, gender, and race, IDUs were 2.4 times more likely than NIDUs to report suicidal ideation [95% Confidence Interval (CI): 1.1-5.2]. However, on further adjustment for homelessness, depressive symptoms, and gay/lesbian/bisexual identity, IDU status was no longer independently associated with suicidal ideation. These results suggest that factors associated with injection drug users' lifestyles and mental health status may account for the higher prevalence of suicidal ideation in IDUs vs. NIDUs. Further study into these associations is warranted in identifying avenues for suicide prevention among these populations.