The purpose of this study was to establish phosphate norms for the first 4 weeks of life for neonates with birthweight (BW) 500 to 1500 g. The study group included 52 consecutively born neonates: group A (n = 24; BW 500 to 1000 g), and group B (n = 28; BW 1001 to 1500 g). Phosphate levels are reported daily (days 1 to 5), and then weekly until week 4. Except for the first 2 days of life, phosphate levels were statistically lower in group A versus group B. A prospective study is required to examine whether phosphate levels can be used as a marker of acuity in neonates and to examine the effect of phosphate repletion on metabolic functions.