The preoptic area of the domestic fowl (Gallus gallus) was studied by means of the Golgi technique. At least two regions can be recognized: (i) a medial and (ii) a lateral area, clearly distinguishable laterally from the adjacent telencephalic regions. The dendritic organization of the preoptic area is quite uniform. The neurons can be classified as isodendritic elements. The magnocellular elements are few and irregularly scattered mostly in the periventricular grey of the medial preoptic area. Of relevant interest is also the observation of some bipolar and horizontal neurons in the dorsal part of the medial preoptic area, near the anterior commissure.