This study determined whether a private room or open ward design better met optimal environmental conditions for a neonatal intensive care unit with regard to sound level, light level, temperature and humidity. Multiple-bed designs for hospital neonatal intensive care units were the standard until recently. Now, private room designs promise to provide better conditions for neonate development and patient care quality. The study compared an eight-bed open ward design with a private room design of a 45-bed neonatal intensive care unit, measuring the environmental parameters of sound, light, temperature, and humidity before and after the construction and occupation of a new private room unit. Average light levels were higher in the private room design because of the increased number of windows, but both designs were within the recommended levels. Mean temperature readings were two degrees cooler in the private room environment, and readings were more stable. Mean humidity readings in the two environments were the same, but humidity levels in the private room design were more stable. Median sound level in the private room design was lower than the open ward design, but the range was similar. The private room design allows for a more controlled patient care environment that can be maintained within a smaller range of variation nearer optimal environmental conditions.