The aim of this retrospective study was to provide quantitative information on the prevalence of dentofacial characteristics to find correlations between them and to determine the orthodontic treatment need in a Belgian orthodontic population. Data were acquired from 1,477 patients who had initial records made at the Department of Orthodontics, Katholieke Universiteit Leuven, Belgium between February 1983 and June 1997. The prevalence of Angle Class I, Class II div. 1, Class II div. 2 and Class III malocclusions was, respectively, 31%, 52%, 11% and 6%. The male-to-female ratio was 4:6. Spacing and trauma to teeth occurred more in males than in females. The prevalence of the following dentofacial characteristics was significantly different between the Angle classes: segmental crossbite; crossbite of one tooth; facial asymmetry; protral and lateral mandibular shift; horizontal and vertical growth patterns, impacted teeth; traumatised teeth; ectopically erupting canines; age at first records. No significant difference in the prevalence of the Angle classes between the sexes was found. Several clinically relevant correlations were found between the examined dentofacial characteristics. This Belgian orthodontic population from the Leuven region seems to be comparable to other orthodontic populations in Europe.