The aim is to estimate HBV prevalence and the associated risks among noninjecting cocaine users (NICUs). In 2002–2003, a total of 824 NICUs from Buenos Aires (Argentina) and Montevideo (Uruguay) were interviewed using a structured questionnaire. Serologic tests were carried out for Human Immunodeﬁciency Virus (HIV), hepatitis B (HBV), syphilis, and others. The population was divided into two serologic groups: HBV-infected and seronegative group. Univariate and binary logistic model were developed. The results seem to indicate that, among NICUs, HBV is transmitted through sexual contact. Prevention measures, including vaccine, are needed in order to control and minimize risks. The study’s limitations are noted.