Morphological and electrophysiological studies on the Mauthner cells of cod (Gadus morhua) were conducted. The results demonstrated that the teleost has fulfilled all four morphological criteria for Mauthner cells. These include conspicuous soma at the level of the 8th cranial nerve, two distinctive dendrites (lateral and ventral) a large axon, and a specific axon cap. A conspicuous ventro-lateral dendrite extended from the soma and branched distally was found in cod. The extracellular antidromic Mauthner cell response is a short latency (1.9 msec), with an all or none negative potential, and characteristically fits the physiological criteria of Mauthner cells.