Prevention programs for intravenous drug users have proven their efficacy in decreasing human immunodeficiency virus transmission but have limited effect on hepatitis C virus (HCV) contamination. A study was conducted to document the presence of HCV genome (HCV RNA) in 620 items of used injecting paraphernalia collected from representative sites. Using sensitive molecular techniques, HCV RNA was not detected on used filters or water vials and was seldom detected on cups (9%). However, HCV RNA was frequently found on syringe pools (38%) and on swabs (82%) at high titers. Our investigation, which was conducted in real injecting settings, highlights swabs as a potential source for HCV transmission.