A new species of heterobranch gastropods, the hammerhead Chelidonura radwanskii sp. nov., found in the socalled Pleurotoma-clays of middle Miocene (Langhian) age in the environs of Korytnica, southern Holy Cross Mountains, Poland, is described. It is the first fossil representative of Chelidonura A. Adams, 1850. This tiny gastropod is named in honour of the late Professor Andrzej Radwański.