Of the injecting drug users (IDUs), 24% had borrowed, and 37% had passed on syringes in the previous 6 months. In logistic regression analysis, current borrowing of syringes was significantly associated with a shorter duration of injecting drug use, a higher number of drug-injecting sex partners in the previous 6 months, and with current lending of syringes. A majority of the IDUs have modified previous HIV risk behaviour but these modifications are insufficient and not sustained over time. Intensified AIDS prevention measures for IDUs in Poland are needed.