Injecting drug users (IDUs) were recruited from the streets of Calcutta to obtain a baseline biological and behavioural data on risk practices. One-fifth of them (mostly using buprenorphine) tested positive for hepatitis B surface antigen (HBsAg); 4% were reactive to serologic test for syphilis (VDRL: Venereal Disease Research Laboratory). Condom use was insignificant while 74% reported sex with female sex workers and 15% of male IDUs also reported having sex with men. Although, sharing of injecting equipment (`works') was perceived as dangerous by the IDUs, majority of them (90/103) reportedly shared it; cleaning of works before sharing was a concern for intravenous but not for intramuscular drug injecting. Half of the IDUs reported suffering ever from abscess; a proportion (12%) of which had had superadded attack of maggots in it. They were also found to be infected with HIV (1%, 95% CI 0.028-5.97%) at a low prevalence that prompted subsequent launching of needle syringe exchange programme, establishment of cleaning norms before sharing of works, cleaning of injecting site on the body and condom promotion.