Background & Aim: Levels of lactic dehydrogenase(LDH) in the cerebrospinal Fluid(CSF) have been used to evaluate a variety of neurologic disorders. However, few studies have been performed on neonates. The aim of this study was to detect levels of this enzyme in normal neonates. Patients and Methods: In this descriptive study, CSF samples were collected from 94 febrile infants 46 aged 0-4 weeks and 48 aged 5-8 weeks. These LDH levels were compared to those of 45 febrile infants with mean age of 10±6/2 months who were suspected of nervous system infection and normal CSF findings. Results: Mean total LDH activity in the CSF was significantly higher in the first month of life than in the second month of life as compared with the control group(p<0.001). Conclusion: We propose evaluation of total LDH activity in CSF of normal neonates according to age.