The Alagille syndrome (AGLS) is a rare condition, with few studies reported in the literature, especially in the field of dentistry. It consists of a disease involving many systemic problems and specific facial features. The liver and heart are the most intensely affected organs, and depending on the severity, it may be necessary to perform transplants. It is an autosomal dominant disease with a variable expressivity, and its prevalence is 1/100,000 live births. Dental findings are conflicting. Some authors claim that dental anomalies occur only in deciduous dentitions; however, there is evidence that permanent teeth can also be affected, as will be described in this paper, through a case report of a patient diagnosed with AGLS, who sought out the Dentistry service at Pontifical Catholic University of Minas Gerais, complaining of a strong stain in her teeth, severe dental crowding, and a facial appearance of prognathism.