ABSTRACT.Twelve full‐term, healthy newborn infants had daily urinary β2 microglobulin, albumin and creatinine levels measured during the first five days of life.A marked elevation in urinary β2 microglobulin was demonstrated. There was a marked variation from day to day with a range of 20–11,000μg/l. The relatively steady creatinine and albumin excretion levels suggest there is a true increased excretion of β2 microglobulin in the neonatal period with a tendency for the excretion rate to rise during the first five days