Peripherally administered n-hexacosanol, a long-chain fatty alcohol, strongly attenuated the degeneration of cholinergic neurons in the medial septum and the vertical limb of the diagonal band of Broca following transection of their dorsal projection to the hippocampus by unilateral fimbria-fornix aspiration. The maintenance of AChE-positive neurons was particularly striking in the vertical limb of the diagonal band of Broca, where 83% of the neurons survived after two weeks of n-hexacosanol treatment compared to 51% in the non-treated animals. This compound has already been found to possess some neurotrophic activities on cultured neurons from rat cerebral cortex. But the present study is the first report of an in vivo neurotrophic influence exerted by an exogenously administered long-chain fatty alcohol. The low dosage needed and the peripheral administration of this compound may be of great advantage in the reduction of cell loss in some neurodegenerative disorders like Alzheimer's disease or stroke.