- The objective of this study was to assess the perceptions of secondary school sports' coaches about oro-facial injuries and mouth protector usage in sports by the adolescent athletes. A 10-item, self-completion questionnaire was distributed to 42 coaches from 23 secondary schools randomly selected from different parts of Ibadan city in Nigeria between May and June, 2002. The questionnaire sought information on why a mouth protector (mouthguard) is used, when it is required; the types of mouth protector used, the major reasons for choosing a specific mouth protector, and personal feeling as to whether mouthguards prevent oral injury. Descriptive statistics were used for the data while the chi-square statistic was employed to test the significance of association between variables. All the coaches, 25 (59.5%) males and 17 (40.5%) females with age range of 19-51 years and mean age of 38.07 +/- 8.97 years (mean +/- SD), completed and returned the forms (100% completion rate). 95.2% of the coaches believed that mouthguards prevent oral injuries and 95.2% of them also would like more information on different types of mouthguard, while 4.8% each felt otherwise. The main factor determining the choice of the type of mouthguard for athletes by the coaches was the quality of oral protection (57.1%), and the next was the cost (23.8%). Acceptance of mouthguard was scored as positive by 88.1% of the athletes. 81.0% of the coaches felt that mouthguard should be worn at all times (during practices and competitions) while 19.0% would prefer the use during competitions only. The majority of the coaches (71.4%) believed that boxing needs mouthguards, 2.4% each indicated football (soccer) and Judo while 11.9% of the coaches did not indicate any sport. The majority of these Nigerian coaches agreed on the protective effectiveness of mouthguard against sport-related oro-facial injuries, but they are yet to be adequately informed about mouthguards generally so as to correctly advise and influence these adolescent athletes in this regard.