: Background: The aim of this study was to evaluate Phenylketonuria (PKU) patients’ oral health habits and the efficiency of tailored recommendations for PKU patients in Latvia on the correct management of oral hygiene. The-free amino acid formula can negatively impact PKU patient’s oral health as it contains a high amount of complex carbohydrates. Materials and methods: In this study with a one-month interval pre and post implementation of oral hygiene recommendations, two questionnaires regarding oral hygiene habits and knowledge were prepared and provided by trained medical personnel to be filled in for all diagnosed PKU patients in Latvia who were not lost to follow-up. Results: Based on the questionnaires among the PKU patients under 18 years of age, 27% cleaned their teeth once a day. However, 6% of patients did not engage in regular teeth brushing at all. Among PKU patients over and 18 years of age, 26% brushed their teeth only once a day. Additionally, a mere 39% of PKU patients ≥18 years of age and 17% < 18 years of age incorporated flossing into their oral hygiene routine. In total, 45% of PKU patients ≥18 years of age and 44% < 18 years of age visited a dentist once a year, but 40% ≥18 years of age and 39% <18 years of age visited a dentist less often than once per year. After reading the recommendations, a remarkable number of PKU patients < 18 years of age had improved their daily oral hygiene routine, including toothbrushing (25%) and flossing (23%). Conclusion: Given the unique dietary requirements and the implementation of these daily at-home oral health practices, motivation and regular reminders should result in better oral health of PKU patients and cooperation with clinicians.