When multilamellar liposome trapping calcein, the fluorescent dye, was suspended in buffered ethanol containing the quencher, cobalt (II) ions, the increase in ethanol concentration in the range of 0-17.5% was accompanied with a striking decrease in fluorescence intensity, suggesting that permeability to the liposome membrane depended upon the ethanol concentration. In buffer containing 17.5% ethanol, as the percentage of phospholipid in which the 1- and 2-positions were occupied by saturated fatty acids increased in PC-PE liposome, there was a progressive decrease in velocity coefficient in quenching fluorescence, and the ratio of PC/PE appeared to have little effect on velocity coefficient. Intracellular nucleotide in cell suspension in 20% ethanol at 15 degrees C appeared to diffuse to the liquid phase by simple diffusion, and palmitic acid-enriched cells showed a lower permeability coefficient P’, compared with linoleic acid-enriched cells, regardless of intracellular ergosterol content. The survival in linoleic acid-enriched cell was less than that of palmitic acid-enriched cells, suggesting that cell viability corresponded with P’.