This study examined the sexual behavioural pattern, knowledge and attitudes to HIV/AIDS of 216 extension personnel in south-west Nigeria. Information was obtained using a combination of structured interview schedule and focus group discussions. Results show that the extension personnel were young men and women, married, mostly Christians and educated. All the women had premarital sex, compared with 98.3% of the men, more men (46.7%) engaged in extramarital sex than women (18.4%), and 81.2% of the men were using condoms regularly, compared to 57.5% women users. All the respondents were fully aware of HIV/AIDS, while 79.5% of men and 85.0% of women expressed negative attitudes to HIV/AIDS. This has serious implications for the delivery efforts of focal extension agencies.