FIG 1: Adult fluke of Nasitrema species from a bottle-nosed dolphin seen by (a) scanning electron microscopy and (b) histology. Haematoxylin and eosin. Bar= 1 mm strand, as demonstrated in the Pacific coast strandings described by Dailey and Walker (1978) and Morimitsu and others ( 1992). Moreover, the high incidence of this parasite in cetaceans stranded on the Canary Islands widens the area of its distribution to the North Atlantic. The anatomical arrangement of the paraotic sinuses, ear complex, eighth cranial nerve and brain supports the idea of the fluke migration route through the nerve as suggested by Ridgway and Dailey (1972) and Morimitsu and others (1992). From a pathological perspective, the absence of parasitic forms does not rule out its participation in nervous lesions, such as non-purulent leptomeningitis, thus supporting the present results which clearly indicate a higher incidence of this parasite than reported previously, possibly because it has been overlooked in most necropsies. This study also reports new cetacean species (pygmy sperm whale, rough-toothed dolphin and Atlantic spotted dolphin) parasitised by Nasitrema species, showing the broad spectrum of odontocetes infected by this parasite.