The hepatocytes of Pimelodus maculatus studied in thin sections revealed: 1. 3 physiological surfaces: a) in content with the Disse's space; b) in contact with neighboring hepatocytes; and c) showing grooves that delimit bile canaliculi; 2. bile canaliculi presenting, sometimes, intracellular diverticula; 3. junctional complexes joining hepatocytes close to the bile canaliculi; 4. gap junctions in great number; 5. a characteristic feature of the RER; 6. a commonly close relationship between mitochondria and RER; 7. Golgi complexes near the bile canaliculi and in the perinuclear area; 8. smooth endoplasmic reticulum, lysosomes, glycogen and lipids in small amounts.