Many organisms produce bioactive substances used in the production of drugs. In this context, Cnidaria occupy a major position; for this reason, research on new bioactive substances has focused upon them as an interesting target. As a matter of fact, substances and extracts able to fight human diseases have been found in cnidarians, several of which have been studied in laboratories using animal models or cell cultures and, at present, some are in the pre-clinical phase. This review aims to highlight the research on existing drugs or new drug candidates extracted from Cnidaria and the recent patents published in this field; furthermore, as many cnidarian venoms are known to have an impact on the CNS and on neuromuscular transmission, this review particularly considers the research concerning CNS drug discovery and pending patents.