Purpose: Knowing the accurate gestational age(GA) is critical in nursing care of premature infants. A descriptive study was performed to examine the reliability and clinical applicability of the New Ballard examination(NBE) in premature infants. Method: A NBE was performed to measure GA by assessing the neuromuscular and physical maturity in the course of physical examination of a convenient sample of 74 premature infants. Result: 1. The highest item of NBE score was posture (mean=2.82) and the lowest item was breast (mean=1.84). 2. There was a highly correlation between both the GA by LMP(GA-LMP) and GA by NBE (GA-NBE)(r=.844, p=.000). 3. There was a greater positive relationship in neuromuscular maturity than physical maturity in the GA-NBE of the premature infants(r=.786 vs r=.933). 4. There was a positive correlation between neuromuscular, physical, total maturity, GA-LMP and GA-NBE in the birth weight, length, 1, 5 minute apgar score. 5. There was no significant difference neuromuscular, physical, total maturity in NBE by delivery history. Conclusion: The study supports the reliability a clinical relevance of NBE in assessment of the accurate GA in premature infants.