Long distance truck drivers (LDTDs) have been identified as one of the groups at higher risk for human immunodeficiency virus (HIV) infection. Understanding how certain social and psychological variables that have a strong theoretical basis contribute to sexual risk behaviour will guide in the implementation process of HIV risk-reduction intervention in the trucking population. In line with the conceptualisation of Information, Motivation and Behavioural skills model, we examined the extent that HIV knowledge, attitude towards condom use, peer support to condom use, perceived vulnerability to HIV/AIDS, and condom use self-efficacy will independently and jointly explain sexual risk behaviours of LDTDs in a haulage company in Lagos, Nigeria. A cross-sectional survey design was used and 154 drivers with ages ranging from 27 to 68 years (M = 44.03, SD = 8.82) completed copies of a questionnaire comprising demographics and measures of psychological variables. Psychological factors that included HIV knowledge, attitude towards condom use, perceived vulnerability to HIV/AIDS, peer support to condom use, and condom use self-efficacy significantly jointly predicted sexual risk behaviours (R
2 = .59, F(5, 148) = 42.63; p < .05), by accounting for about 59% of the explained variance in sexual risk behaviours. Social factors that included age, number of years of education, number of wives, number of intercourses in the last three months, number of partners apart from primary partners, and number of weeks spent outside home significantly jointly predicted sexual risk behaviour (R
2 = .15, F(6, 147) = 4.39; p < .05) by accounting for about 15% of the explained variance in sexual risk behaviour among the drivers. It is concluded that all the psychological and social factors examined as predictor variables could jointly play important roles in prevention intervention programmes for reducing sexual risk behaviours of LDTDs. Stakeholders should sensitise LDTDs on the need to realise that they are a high-risk group and are more vulnerable to HIV infection; thus, behaviour change is indispensable in their sexual relationships.