The authors studied the morphology and anatomy of the olfactory organs of the marine fish Thynnus thunnina. The fish has a single nasal orifice. The round olfactory rosette has a central axis surrounded by radially oriented lamellae. The olfactory rosette (olfactory organ) is provided with two accessory nasal sacs - a lacrimal and an ethmoidal sac. Thynnus thunnina was classified in Teichmann's (1954) group II, i.e., the "eye-fishes", whose vision is better developed than their olfaction.