Diethyl phthalate (DEP; CAS No. 84-66-2) has many industrial uses, as a solvent and vehicle for fragrance and cosmetic ingredients and subsequent skin contact. This review focuses on its safety in use as a solvent and vehicle for fragrance and cosmetic ingredients. Available data are reviewed for acute toxicity, eye irritation, dermal irritation, dermal sensitization, phototoxicity, photoallergenicity, percutaneous absorption, kinetics, metabolism, subchronic toxicity, teratogenicity, reproductive toxicity, estrogenic potential, genetic toxicity, chronic toxicity, carcinogenicity, in vitro toxicity, ecotoxicity, environmental fate and potential human exposure. No toxicological endpoints of concern have been identified. Comparison of estimated exposure (0.73 mg/kg/day) from dermal applications of fragrances and cosmetic products with other accepted industrial (5 mg/m(3) in air) and consumer exposures (350 mg/l in water; 0.75 mg/kg/day oral exposure) indicates no significant toxic liability for the use of DEP in fragrances and cosmetic products.