Although long distance truck drivers have been implicated in the spread of HIV in Africa, there is a paucity of studies of their sexual cultures. This paper reports on a study of the sexual culture of drivers, mediators and commercial sex workers (CSWs) in a roadside truck stop on the Trans-Africa highway in south west Uganda. Sixty-nine truck drivers, six middlemen and 12 CSWs were interviewed using semi-structured questionnaires. Interviewing truck drivers also entailed participating in the town's nightlife and spending much time in the bars. Truck drivers stop briefly at the truck stop for various reasons: to eat, sleep, have sex and sell goods they are carrying. Middlemen mediate the latter two activities. Middlemen buy goods from the drivers and introduce them to 'suitable' women with whom they can have casual sex. Most drivers have sex when they spend the night at the truck stop, and most make use of the services of the middlemen. The most important reasons why drivers use middlemen are that the latter speak the local languages and, in particular, know the trustworthy and 'safe' (HIV-negative) women. The CSWs use middlemen mainly because they are a guarantee that the driver will pay and they usually ensure that drivers pay well. The mediation system is becoming increasingly professionalized. Most drivers claimed to use condoms during casual sex, and this was confirmed by the CSWs. General use of condoms is encouraging, particularly given the context of a culture generally opposed to condoms. The idea that middlemen can recognize 'safe' women is worrying. However, given their key position, middlemen could form the hub of an opinion leader type intervention focused on drivers and the professional group of sex workers described here, providing condoms, advising about the importance of condom use in all casual sexual encounters, giving information about HIV and STDs, and possibly referring drivers and women to appropriate sources of HIV counselling and testing and STD treatment.