Because of the effects of ethanol used as a solvent in other experiments, the action of aliphatic alcohols on leaf senescence in the dark has been studied systematically. These compounds both maintain chlorophyll and prevent proteolysis in the dark, much as do the cytokinins and other senescence-delaying substances. The activity of the straight-chain alcohols increases in a log-linear fashion with increasing chain length up to 1-octanol. Introduction of a branch in the chain or of a second OH group greatly decreases, or in some cases annuls, the antisenescence activity. In all cases, the action on senescence is closely (although not always exactly) paralleled by opening of the stomata. Abscisic acid and exposure to high concentrations of osmoticum, both of which close the stomata, antagonize the action of the alcohols. Some interactions with other agents are noted. The effects are compared with reported effects on seed germination, on hemolysis and animal membranes, and especially on permeability to K(+) ions, and a tentative basis for the mechanism of action is advanced.