The aim of this study was to determine the occurrence of oral health impacts among patients with severe malocclusions and dentofacial deformities before treatment. A further aim was to evaluate the effect of gender or the type of malocclusion on the oral impacts. The study comprised 151 adult patients who were referred for orthodontic or surgical-orthodontic treatment to the Oral and Maxillofacial Department, Oulu University Hospital, Finland during the years 2001-2004. The study group consisted of 92 females and 59 males with a mean age of 35.5 years [standard deviation (SD) 11.5 years, range 16-64 years]. A self-completed Oral Health Impact Profile (OHIP)-14 questionnaire was used to measure oral impacts during a 1 month reference period. The prevalence, extent, and severity scores were calculated from the OHIP-14. Malocclusions were registered at clinical examination. The prevalence and mean extent and severity scores were compared among malocclusion groups and between genders. Statistical significance was evaluated with Mann-Whitney, Kruskall-Wallis, Chi-squared, and Fisher's exact tests. The prevalence of oral impacts perceived fairly or very often was 70.2 per cent. The mean severity and extent scores were 17.2 (SD 10.5, range 0-45) and 2.5 (SD 2.6, range 0-10), respectively. Physical pain as well as psychological discomfort and disability were the most commonly perceived oral impacts. Being self-conscious, feeling tense, having difficulties in relaxing, and being somewhat irritable with other people were more common in females than in males. No differences were observed in oral impacts among the malocclusion groups. Compared with a 'normal' population, patients with severe malocclusions report high levels of oral impacts. Females reported oral impacts more often than males.