Abstract. OBJECTIVES: To determine the frequency of tracheal pepsin in ventilated neonates and whether the angle of head elevation was associated with tracheal pepsin. STUDY DESIGN: Serial trachael samples (at 3, 7, 14, 21 and 28 days of ventilation) were obtained from intubated, ventilated very low birth weight infants. Presence of tracheal pepsin was determined by Western blot analysis using a specific anti-human pepsin antibody. RESULTS: Tracheal pepsin was detected in 35/66 (53%) of the ventilated neonates (birthweight: 798 ± 268 grams [mean ± standard deviation]). Neonates whose head elevation was in the upper quartile (≥14 degrees) during the first sampling time (day 3) were less likely (4/16 vs 9/10, P = 0.0013) to have tracheal pepsin when compared to neonates whose head elevation was in the lowest quartile (≤8 degrees). CONCLUSIONS: Pepsin, a marker for gastric secretion aspiration, was detected in 53% of ventilated low birth weight neonates; early elevation of the head of the bed was associated with a lower rate of tracheal pepsin.