‘Magun’ is a Yoruba traditional magic against sexual promiscuity. It is the harnessing of supernatural forces inherent in mystical materials, rites, and spells to prevent, expose, or punish a promiscuous woman, her lover, or both. ‘Magun’ magic exhibits parallel characteristics with other magic in Yorubaland, Nigeria, with respect to structure. At the same time, ‘magun’ has characteristics which differ from those posited by many accepted contemporary theories of magic. ‘Magun’ is not easily affected by conventional taboos. ‘Magun’ does not fit into Raymond Firth’s classification of magic as either productive, protective, or destructive. Different types of ‘magun’ can be classified under each of these categories, while any particular ‘magun’ can be productive, protective, and destructive at different times. ‘Magun’ is neither good nor bad. Rather, it is the use to which ‘magun’ is put that determines whether it is productive, protective, or destructive. E.E. Evans-Pritchard’s thesis that magic is an aid, a catalyst to human effort, does not apply to ‘magun’, which, rather than acting as an aid, initiates action and completes it. Moreover, unlike other magic, ‘magun’ is impartial in that it can work effectively on the innocent and the guilty alike. App., ref. (Also published in: Africana Marburgensia, vol. 32, no. 1/2 (1999), p. 28-56.)