Myristicin, or methoxysafrole, is the principal aromatic constituent of the volatile oil of nutmeg, the dried ripe seed of Myristica fragrans. Myristicin is also found in several members of the carrot family (Umbelliferae). Several intoxications have been reported after an ingestion of approximately 5 g of nutmeg, corresponding to 1-2 mg myristicin/kg body weight (b.w.). Although these intoxications may be ascribed to the actions of myristicin, it is likely that other components of nutmeg may also be involved. The metabolism of myristicin resembles that of safrole. No information is available, however, concerning the quantitative importance of the different metabolic pathways. The acute toxicity of myristicin appears to be low. No toxic effects were observed in rats administered myristicin perorally at a dose of 10 mg/kg b.w., while 6-7 mg/kg b.w. may be enough to cause psychopharmacological effects in man. A weak DNA-binding capacity has been demonstrated, but there are no indications that myristicin exerts carcinogenic activity in short-term assays using mice. Intake estimations indicate that nonalcoholic drinks may be the most important single source of myristicin intake. Based on available data, it seems unlikely that the intake of myristicin from essential oils and spices in food, estimated to a few mg per person and day in this report, would cause adverse effects in humans. It is, however, at present not possible to make a complete risk assessment, as studies regarding genotoxicity and chronic toxicity, including reproductive toxicity and carcinogenicity, are still lacking.