Проаналізовано проблемні питання змісту та форм використання спеціальних знань під час розслідування неналежного виконання професійних обов’язків медичним або фармацевтичним працівником. This article carries material about concepts and features of application of expertise during the investigation of improper execution of professional duties by medical or pharmaceutical employees. At the beginning it deals with the views of different scientists which became the theoretical basis and allowed to form a holistic view of expertise. Also, certain medical specialties, which have specific knowledge, missing investigators in the process of professional activities was determined.