The present study was performed on a population of subjects assisted at the dental clinic of Instituto Superior de Ciências da Saúde-Norte. The aims of the study were: (1) to analyse the prevalence of supernumerary teeth, (2) to characterise its gender distribution, and (3) to investigate the repercussions of supernumerary teeth over neighbouring teeth and tissues. From the records of all the patients received from 1993 to 2000, 16771 clinical files contained panoramic X-ray plates (8712 females and 8059 males) and were selected. A total of 151 supernumerary teeth were found in 127 patients (72 males and 55 females, aged from 5 to 63 years), corresponding to a prevalence of 0.76%. Other designed important issues were one supernumerary teeth for individual; the mesiodens type (followed by the 4th molar); conical morphology; the maxilla (namely on the maxillary medial line): location as predominant findings. Evolutionary state, 47 (31.1%) were erupted and 104 (68.9%) unerupted. In most cases 108 (71.5%), the radiological images didn't suggest alterations on adjacent teeth and/or tissues. The repercussions found, potentially associated to supernumerary teeth were: 12 (7.9%) displacement of adjacent teeth, nine (6%) delayed eruption of permanent teeth, and eight cases (5.3%) diastema formation.