Six bowhead whale stomachs were examined grossly in the fixed state. Histologic sections representing the proximal stomach chambers of 5 bowheads were studied. The bowhead stomach is compartmentalized, consisting of the forestomach, fundic chamber, connecting channel, and pyloric compartment. The largest compartment, the forestomach, is a dilated extension of the esophagus with a whitish mucosa characterized by abundant, multidirectional infolding. It is nonglandular and, like the esophagus, is lined by a stratified squamous epithelium with a tendency for cornification. The mucosa of the fundic chamber is reddish brown and marked by large folds which are arranged mainly longitudinally. Gastric pits, lined by mucous cells, lead into mucous glands in the initial portion (cardiac region) of the fundic chamber. In the remainder of the chamber, the glands contain mucous neck cells, parietal cells, and chief cells. The connecting channel is a tubular structure (about 3 cm internal diameter) which passes from the mid-region of the fundic chamber to the pyloric compartment. This last chamber is also tubular but with a consistently larger lumen.