Abstract 1. 1. The effects of drugs on the tonus changes of longitudinal smooth muscles of the stomach of the cod, Gadus morhua, were studied on isolated preparations. 2. 2. Contractions caused by sympathomimetic drugs seem to be due to activation of α-receptors. Evidence for the presence of ß-receptors causing relaxation was also obtained. 3. 3. Electrical stimulation of the vagus nerve caused contraction, which is depressed by bretylium and the α-blocking agent phenoxybenzamine. This indicates the presence of adrenergic fibers in the vagus nerve. 4. 4. Contractions produced by electrical stimulation of the vagus nerve, or by adrenergic drugs, are inhibited by atropine. This may indicate that the effects are mediated via cholinergic neurons.