AbstractObjective:To measure the prevalence of food insecurity and explore related characteristics and behaviours among people who inject drugs (PWID).Design:Cross-sectional analysis of a community-based programme for HIV infection among PWID (ARISTOTLE programme). Food insecurity was measured by the Household Food Insecurity Access Scale. Computer-assisted interviews and blood samples were also collected.Setting:A fixed location in Athens Metropolitan Area, Greece, during 2012–2013.Participants:In total, 2834 unique participants with history of injecting drug use in the past 12 months were recruited over four respondent-driven sampling rounds (approximately 1400/round).Results:More than 50 % of PWID were severely or moderately food insecure across all rounds. PWID were more likely to be severely food insecure if they were older than 40 years [adjusted OR (aOR): 1·71, 95 % CI: 1·33–2·19], were women (aOR: 1·49, 95 % CI: 1·17–1·89), from Middle East countries (aOR v. from Greece: 1·80, 95 % CI: 1·04–3·11), had a lower educational level (primary or secondary school v. higher education; aOR: 1·54, 95 % CI: 1·29–1·84), had no current health insurance (aOR: 1·45, 95 % CI: 1·21–1·73), were homeless (aOR: 17·1, 95 % CI: 12·3–23·8) or were living with another drug user (aOR: 1·55, 95 % CI: 1·26–1·91) as compared with those living alone or with family/friends. HIV-infected PWID were more likely to be severely food insecure compared with uninfected (59·0 % v. 51·0 %, respectively, P = 0·002); however, this difference was attributed to the confounding effect of homelessness.Conclusions:Moderate/severe food insecurity was a significant problem, reaching > 50 % in this sample of PWID and closely related to socio-demographic characteristics and especially homelessness.