This study, perhaps the first of itskind in this region, is based on a study that explores thepractice of casual sex among truck drivers and commercialsex workers in the border areas of Poland and Lithuania at apoint of time, and uses this evidence to extrapolate thepotential impact on the spread of HIV/AIDS in thesecountries. After the Introduction which provides background,Section 2 reviews similar studies carried out elsewhere inthe world. Section 3 describes the methodology employed inthis study, followed by a brief description of the data inSection 4. Section 5 contains a discussion of the resultsand policy implications.