In mixtures of substances with different taste qualities, the components can still be recognized but are usually perceived as less intense than when unmixed. Responses of electric potential in an artificial lipid-membrane to several taste substances such as HCl, quinine and NaCl were investigated. In the presense of another taste substance, responses of membrane potential to each taste substance were suppressed markedly. Pretreatment of the membrane with anesthetic tetracaine or bitter substance quinine also suppressed the response to quinine, HCl and NaCl; the suppression could be attributed to adsorption of tetracaine or quinine to the membrane.