AIMS--To evaluate the development and course of Bell's phenomenon (BP) in premature and normal neonates. METHODS--Twenty seven preterm infants and 42 healthy full term infants were studied. Mean birth weight, gestational age, and head circumference were recorded. BP was graded from no response to full response. The premature group was examined in the first week of life, and then at 4 and 8 weeks after birth. The full term group was initially examined at the age of 3 days until a full response was observed. RESULTS--No preterm infants exhibited BP during the first week of life, while 8/28 (29.6%) exhibited a weak to full reflex at 8 weeks of age. In the full term group 15/42 neonates (35.7%) demonstrated a mature reflex at age of 3 days and 36/37 (97.3%) at age 16 weeks. A significant correlation was observed between BP, sex, and birth weight, as well as gestational age in the premature group. No such correlation was found in the full term infants. CONCLUSION--BP has a longitudinal course. It is an important clinical marker for evaluation and follow up of neuro-ophthalmic maturation in neonates.