Background: The aim of this study was to know the distribution of dental developmental alterations in the population requesting stomatological attention at the Admission and Diagnosis Clinic of our institution in Mexico City. Material and Methods: We reviewed the archives and selected those files with developmental dental alterations. Analyzed data were diagnoses, age, gender, location and number of involved teeth. Results: Of the 3.522 patients reviewed, 179 (5.1%) harbored 394 developmental dental alterations. Of them, 45.2% were males and 54.8% were females with a mean age of 16.7 years. The most common were supernumeraries, dental agenesia and dilaceration. Adults were 30.7% of the patients with dental developmental alterations. In them, the most common lesions were agenesia and supernumeraries. Mesiodens was the most frequently found supernumerary teeth (14.7%). Conclusions: Our finding that 30.7% of the affected patients were adults is an undescribed and unusually high proportion of patients that have implications on planning and prognosis of their stomatological treatment.