The Eustachian (or auditory) tube is of central importance for the regulation of ambient air pressure changes within the middle ear spaces. Dysfunction of the Eustachian tube usually leads to chronic inflammatory changes of the middle ear. The aim of the present feasibility study was to investigate an alternative, minimally invasive approach for the application of fluids to the middle ear via the Eustachian tube. This so-called transtubal application (TTA) was conducted in a prospective, non-randomized study with a total of ten subjects. The TTA approach consisted of placing a microendoscope within the Eustachian tube under local anaesthesia via its epipharyngeal opening. Subsequently, fluids were applied through an additional working channel after microendoscopic evaluation. Therefore the subjects were positioned supine-laterally and had to swallow actively. The successful fluid application into the middle ear was evidenced by microendoscopy of the tympanic membrane (visualization of the fluid level). In all cases, a successful application could be evidenced. Side effects (e.g. pain, mucosal injuries, microbleedings) were not observed. This new technique (TTA) offers the opportunity of a minimally invasive approach to treat tubal dysfunction and possibly other middle ear diseases by local fluid and/or drug application.