The relative size of the encephalon and its parts were studied in samples of the eyed catfish,Pimelodella transitoria(Ribeiro 1912), and of two populations of the troglobiticP. kronei(Ribeiro 1907), from a karstic area in Southeastern Brazil. The size of the olfactory organ and number of olfactory lamellae were also compared. General structure of the brain and olfactory organ were similar to that of other catfish that have been studied and probably correspond to a “Siluriform pattern”.