Wearing mouthguards while playing contact sports reduces the prevalence and severity of orofacial injuries. We report on a 1991-92 promotion of mouthguard use among amateur football players in Melbourne. Four questionnaires were completed by players (1991 season: middle: n = 638, 49 per cent response: late: n = 770, 51 per cent: 1992: early: n = 505, 26 per cent: late: n = 698, 54 per cent), in four age groups (16-19, 20-23, 24-29, 30-44 years), about perceived mouthguard value and usage, injury experience, and awareness of a promotional message. Over the two seasons, mouthguard ownership and consistent wear increased and dental injuries decreased. Ownership of mouthguards increased among: 20-23 year olds and 30-44 year olds (13 and 16 per cent); managers, tradespersons, salespersons, labourers and the unemployed (14-19 per cent); residents of northern and western regions (12 and 13 per cent); those with 6 to 10 years of education (29 per cent); players in old boys' networks (13 per cent); and those with English as a first language (8 per cent). Consistent wear was high at matches (89 per cent) but low at training (13 per cent), owing to perceived lack of physical contact. Of dental injuries reported by 25-31 per cent, fractures predominated over luxations and avulsions. Fractures and avulsions were more common at matches than training; luxations predominated at training. When a mouthguard was not worn, the likelihood of a fractured or avulsed tooth was at least twice that when a mouthguard was worn. Some injuries occurred despite the wearing of mouthguards. The promotional message appeared effective in increasing mouthguard use; newspapers and football journals provided effective message locations for players, and ground signs and the electronic scoreboard for spectators.