INTRODUCTION AND AIMS: Homelessness status is strongly correlated with higher rates of substance use. Few studies, however, examine the complex relationship between housing status and substance use in people who inject drugs (PWID). This study extends previous research by comparing the physical and mental health status and service utilisation rates between stably housed and homeless PWID. DESIGN AND METHODS: A cross-sectional sample of 923 PWID were recruited for the 2012 Illicit Drug Reporting System. Multivariate models were generated addressing associations between homelessness and the domains of demographics; substance use; and health status, service utilisation and criminal justice system contact, with significant correlates entered into a final multivariate model. RESULTS: Two-thirds of the PWID sample were male. The median age was 39 years and 16% identified as Indigenous. Almost one-quarter (23%) reported that they were homeless. Homeless PWID were significantly more likely to be unemployed [adjusted odds ratio (AOR) 2.83, 95% confidence interval (CI) 1.26, 6.34], inject in public (AOR 2.01, 95% CI 1.38, 3.18), have poorer mental health (AOR 0.98, 95% CI 0.97, 1.00), report schizophrenia (AOR 2.31, 95% CI 1.16, 4.60) and have a prison history (AOR 1.53, 95% CI 1.05, 2.21) than stably housed PWID. DISCUSSION AND CONCLUSIONS: Findings highlight the challenge of mental health problems for homeless PWID. Our results demonstrate that further research that evaluates outcomes of housing programs accommodating PWID, particularly those with comorbid mental health disorders, is warranted. Results also emphasise the need to better utilise integrated models of outreach care that co-manage housing and mental health needs.