Naphthenic acids and metal naphthenates (esp. of Cu and Zn) are poor fungicides. Toxic doses of naphthenates to termite (50 kg./cu. m. and more) are so high that these compds. are vitually of no use as wood-preserving agents. The fungicidal and insecticidal properties of metal naphthenates are compared with effective preservatives, e.g. low-chlorinated naphthalene and pentachlorophenol.