OBJECTIVE: To study the dynamic changes of serum neuro peptide Y (NPY) and calcitonin-gene related peptide (CGRP) in neonates with hypoxic-ischemic encephalopathy (HIE). METHODS: Forty-two neonates with HIE (Group A) and 30 normal neonates (controls, Gruop B) were enrolled in this research. Their serum contents of NPY and CGRP were measured with the radio-immuno-assay, and the cranial blood flow was recorded at the same time. RESULTS: The serum NPY content in Group A was significantly higher than that in Group B, especially on day 2 to day 3 following asphyxia [(168.3±10.9) ng/L vs (86.7±5.4) ng/L]( P <0.01). The serum CGRP content in Group A was lower than that in Group B, especially on day 2 to day 3 after asphyxia [(48.4± 3.7) ng/L vs (81.3±6.8) ng/L] ( P <0.01). CONCLUSIONS: NPY and CGRP might be important factors in the development of HIE. The dynamic measures of NPY and CGRP contents might be useful in determining the clinical management of HE. [Chin J Comtemp Pediatr, 2003, 5(1): 27 - 28]