This study examined the psychosocial determinant of middle and older adults sexual behaviour in Ile-Ife. The specific objectives of the study seeks to examine the influence of age on the sexual behaviour of middle and older adults. Also, to examine the influence of self-concept and intimacy on the sexual behaviour of middle and older adults. In addition to the foregoing, the study examined the influence of socio-demographic characteristics on the sexual behaviour of middle and older adults.Primary data were collected from adults in Ife Central L.G.A.. The sample consisted of 375 adults using a multi-stage sampling procedure. Data collected were subjected to statistical analyses.The results showed that the pattern of sexual behaviour, that is, holding hands, hugging, kissing, fondling, caressing, vaginal sex, use of condom with spouse and someone other than spouse, transactional sex are more prevalent among middle adults than older adults while oral and anal sex are more prevalent among older adults than middle adults. The result also showed that age, family type, marital status, occuaption, self concept and intimacy had a significant influence on adults’ sexual behaviour.