Blood-borne infectious diseases such as Human Immunodeficiency Virus (HIV)and Hepatitis C Virus (HCV) spread when the addicts share needles and injecting equipmentwithin contact networks. A quantitative cross-sectional study was conducted in Winnipeg,Canada in December 2003 - September 2004. Through a special questionnaire, respondentswere asked to answer questions about themselves and about their contacts, about relationshipsand how they shared syringes and other injection supplies. Blood tests were used to identifywhether they carried any blood-borne infectious diseases. We selected some variables from theoriginal data set. The purpose was to explain who shared syringes and why these particularindividuals shared syringes. The key finding was that injection drug users were more concernedabout the health of others than their own health; this was shown particularly when it came tosharing of needles. Respondents chose to use their contacts needles despite knowing that thecontact was HCV positive, they were more cautious regarding HIV-infected contacts. Womenshared syringes to a greater extent with their sexual partners, while men more frequently sharedsyringes with his drug connections. It was also shown that ethnicity played a role regarding thesharing of needles.