The upper respiratory mucosa has been reported to react to sex hormones in both physiological and pathological conditions. The present study was specifically aimed to determine the influence of high levels of oestrogen on Eustachian tube function. Fifty-three healthy, pregnant women were prospectively evaluated for Eustachian tube function during pregnancy. Eustachian tube function was found to be highly variable in different women, and in the same woman at different stages of pregnancy. We did not find a specific trend in Eustachian tube function with increasing oestrogen levels as encountered during pregnancy.