The diagnosis of perinatal asphyxia is often inexact and present techniques for assessing its severity are unsatisfactory. The purpose of this study was to describe prospectively the value of the urinary uric acid to creatinine (UA/Cr) ratio in showing increased uric acid excretion in early spot urine samples for the identification of perinatal asphyxia, and to assess the relationship between the urinary UA/Cr ratio and the severity of hypoxic-ischemic encephalopathy. Twenty-seven fullterm infants with perinatal asphyxia were compared with 40 healthy controls. The UA/Cr ratio was higher in the asphyxiated group when compared with controls (2.11 +/- 0.83 vs 0.72 +/- 0.39 P < 0.001). Furthermore, there was a correlation between the UA/Cr ratio and the severity of the encephalopathy (r = 0.84; P < 0.001). The UA/Cr ratio was found to be a good, simple screening test for the early assessment of perinatal asphyxia.