The acoustic reflection method (ARM) is a non-invasive technique which uses the reflection of acoustic waves to measure the cross sectional area of nasal cavities in adults and patency of endotracheal tubes. Characteristics and volume of normal nasal cavities in pre-school children has so far not been studied. Objective: The aim of this study was to determine the optimal ARM recording and the minimal cross-sectional area (MCA) and volume (NV) values in healthy children. Design: Prospective monocentric study using the ARM in pre-school children (<6 years of age). Results - discussion: Seventy children (age 2 to 5) were included in the study. Reliable measures were difficult to obtain in children younger than 2 years of age. The use of a standard nosepiece and a single-use surgical filter enabled reliable, serial recordings. Mean MCA values were 0.46, 0.53 and 0.58 cm2 in the 24-35, 36-47 and 48-60 months-old age groups, respectively. Mean NV values were 2.14, 2.59, and 2.86 cm3 in the same age groups. The MCA and NV values were significantly correlated with height, age and weight. In conclusion, the ARM is feasible in children over the age of 2 and seems to be a promising non-invasive tool to study the nasal cavity patency, anatomy, and volume.