To present patients with hyperphenylalaninemia (HPA) diagnosed by routine newborn screening and to discuss the principles in managing hyperphenylalaninemia, retrospective clinical chart review was conducted. Newborn screening for phenylketonuria (PKU) was performed using the Guthrie Test or Bacterial Inhibition Assay, utilizing dried blood spots on special filter cards. Positive screens were confirmed through plasma amino acid determination, urinary pterins for tetrahydrobiopterin deficiency, enzyme analysis. Once confirmed, the patients were kept on low-phenylalanine diet and regularly monitored for blood phenylalanine levels and developmental profile. A total of 189,720 newborns were screened from 1996--2001. Seventy five screened positive for PKU; 41 returned for retest; 3 were confirmed positive for HPA. This paper presents the first two cases of HPA detected by the Philippine Newborn Screening Program. The management of each case upon diagnosis is discussed. The significance of early detection and treatment of HPA is emphasized.