Viral vectors are widely used in gene therapy due to their efficiency. In this paper we describe a novel method for transfecting the whole inner ear of a guinea pig using adenoviral vectors. Very small perforations are made in both the cochlea and lateral semicircular canal, into which 50 microl of adenoviral suspension (8.9x10(8) plaque forming unit (PFU)/ml) is gently infused. Any excess suspension flows out through the perforation in the semicircular canal and therefore makes no contact with the central nervous system. Our method can therefore be utilized to perform homogeneous gene transfer and may eliminate any effects on other organs, such as the contralateral ear.