The primary aims of this study were to examine Croatian truck drivers' sexual contact with sex workers, estimate the frequency of condom use, and assess knowledge of HIV/AIDS within this population. The research was conducted from June 14 to September 16, 2005 at customs offices and accompanying parking lots in four Croatian cities. The sample consists of 69 truck drivers. Information about sexual behavior and condom use were gathered by using a semi-structured interview. Knowledge of HIV/AIDS, measured with a self-administered questionnaire, was found to be low. Six respondents (8.7%) had correctly answered all 13 questions. By contrast, 73% of drivers considered themselves well informed about HIV/AIDS, indicating that most drivers overestimate their knowledge. The majority of respondents (n=62) assumed that most of their colleagues engage in sexual contact with sex workers while on the road, although only one third of respondents reported that they personally have paid for sex. All of the respondents who reported engaging in sexual contact with sex workers stated that they always use condoms. Fear of being infected with a sexually transmitted infection was reported as the main reason for condom use.