Background: The increasing health problem of hepatitis C virus (HCV) infection has only recently attracted the attention of psychosocial research, especially among subjects at higher risk (e.g. intravenous drug users; IDUs). The aim of the present study was to compare emotional stress symptoms, psychosocial variables (i.e. social support, external locus of control and emotional repression) and coping strategies in HCV-seropositive, human immunodeficiency virus (HIV)-seropositive and HCV/HIV-noninfected IDUs. Methods: IDUs followed by the Infectious Diseases Outpatient clinic were enrolled in the study over a period of 1 year. HCV-positive (n = 62) and HIV-positive (n = 76) IDUs and HCV/HIV-seronegative IDUs (n = 152) completed the Brief Symptom Inventory, the Social Provision Scale, the Locus of Control scale and the affective inhibition scale of the Illness Behavior Questionnaire. Coping with illness among HCV-positive and HIV-positive subjects was assessed through a modified version of the Mental Adjustment to Cancer Scale. Results: No significant differences were found between the samples with respect to individual and interpersonal variables. HCV-positive subjects showed higher scores on several psychological stress dimensions (i.e. obsessive-compulsive, phobic anxiety, paranoid ideation, psychoticism) and lower scores on fighting spirit, hopelessness and anxious preoccupation towards illness than HIV-positive patients. HCV-positive and HCV/HIV-seronegative IDUs reported comparable scores on most of the psychological measures. Conclusions: The findings indicate that routine assessment of psychosocial variables and coping mechanisms should be integrated into all HCV and HIV services, especially those dedicated to treatment of patients with substance abuse, as a vulnerable segment of the population at risk for life-threatening physical illness such as HCV and HIV infections.