We conducted this study to determine the factors associated with high-risk sexual behaviour and condom use among men and women who participated in the 1996 Tanzania Demographic and Health Survey (TDHS); and to assess changes in sexual behaviour between 1991/92 and 1996 TDHS. Respondents were regarded to have practised high-risk sexual behaviour if they were married or cohabiting and had other regular or non-regular sexual partners; or if they were unmarried and had non-regular partners or multiple regular partners. About 8% of women and 29% of men practised high-risk sexual behaviour. High-risk sexual behaviour was common among younger men and women, and decreased with increasing level of education in women. Respondents who were unmarried, Muslims and those who perceived themselves at increased risk of HIV/AIDS were more likely to practise high-risk sexual behaviour. About 4% of women and 15% of men reported to have used condoms during their last sexual encounter. Condom users were significantly more likely to practise high-risk sexual behaviour. Overall, no major changes in sexual behaviour and condom use were observed during the period between the two surveys. Predictors of high-risk sexual behaviour and condom use identified in this report provide valuable information that can be used to design targeted HIV/AIDS interventions in Tanzania.