The venomous pelagic coelentrate Physalia species (Blue bottle) or the Portuguese man-o'war has recently been studied in detail due to their hazardous effects on community. It was observed that the venom of the animal is lethal to man and can also produce cutaneous stings of varying severity. Physalia species also possess significant cardiotoxicity to man, rats, mice and are lethal to lower animals. Thu effect has been attributed to the abnormality in ionic transport across membranes. The cutaneous pain and musculotoxic action in human produced by Physalia venom may be induced by one or several high molecular weight polypeptides. Blockage of specified neurons and neuromuscular junction besides alteration in end plate potential (EPP) and end plate current (EPC) was also attributed to high molecular weight toxic fractions. Survey of enzymatic contents of Physalia venom reveals the presence of a wide variety of enzymes whose presence and actions were similar to that of complex enzyme mixture of snake venom. Besides these clinical manifestations neurotoxicity cytotoxicity and other physiopharmacological effects were also demonstrated.