The effects of the glycoalkaloids alpha-solanine, alpha-chaconine and alpha-tomatine on different cell types were studied in order to investigate the membrane action of these compounds. Hemolysis of erythrocytes was compared to 6-carboxyfluorescein leakage from both ghosts and erythrocyte lipid vesicles, whereas leakage of enzymes from mitochondria and the apical and baso-lateral side of Caco-2 cells was determined. Furthermore, the effects of glycoalkaloids on the gap-junctional communication between Caco-2 cells was studied. From these experiments, it was found that glycoalkaloids specifically induced membrane disruptive effects of cholesterol containing membranes as was previously reported in model membrane studies. In addition, alpha-chaconine was found to selectively decrease gap-junctional intercellular communication. Furthermore, the glycoalkaloids were more potent in permeabilizing the outer membrane of mitochondria compared to digitonin at the low concentrations used.