Octylamine, dodecylamine, octadecylamine and triethanolamine salts ofβ-dodecyloxy- andβ-tetradecyloxypropionic acids, without or with one and with two oxyethylene groups between the alkoxy group and the propionic acid group, were prepared and examined as the growth inhibiting agents againstStaphylococcus aureusandPenicillium. Some of them were also tested againstTrichophyton asteroides, T. interdigitale, T. granulosus, Epidermophyton floccosumandMicrosporum canis. The effects of the alkyloxy, oxyethylene and amine groups on antibacterial and antifungal activities were determined. The dodecyl radical was more potent than the tetradecyloxy radical. The enhancing effect of the oxyethylene group was obscure in the amine salts. The most effective amine was dodecylamine and its salt ofβ-dodecyloxypropionic acid showed almost the same effectiveness as that of its mercury salt againstTrichophyton. As for the soluble amine salts, it was confirmed that their surface activities had nothing to do with their antibacterial and fungicidal powe