Phenylketonuria is an inborn error of autosomal recessive genetic metabolism, with partial or total deficiency of the hepatic enzyme phenylalanine hydroxylase, which converts L-phenylalanine into tyrosine, causing accumulation of phenylalanine at brain and serum levels, interfering with brain protein synthesis causing several damages. This study aimed to characterize patients diagnosed with phenylketonuria at the Neonatal Screening Reference Service from 2008 to 2017. Cross-sectional analytical study with a quantitative approach with retrospective data collection from medical records and databases. Data were grouped as baby gender, date of birth, time of birth and neonatal screening examination collection, type of delivery, gestational age and prenatal status, place of origin, phenylketonuria classification and coverage rate of neonatal screening. The sample consisted of 14 patients, where 64% were male, all mothers had prenatal care and the percentage of cesarean delivery prevailed with 57.2%. Of these 85.7% reside in other states of the country and on the classification of the type of phenylketonuria 64.3% have mild phenylketonuria, as for the coverage rate there was a drop in the number of collections in the reference service. This research contributed to characterize the patient diagnosed with phenylketonuria, which allows greater knowledge about the disease carriers, as well as favoring the reduction of irreversible sequels, expenses and morbidity.