The phytochemical investigation of Casimiroa edulis Llave et Lex (Rotaceae) afforded four coumarins: umbelliferone (1), esculetin (2), imperatorin (3) and xanthotoxol (4). The identification of these compounds was achieved by using a combination of m.p., UV, EI-mass, ¹H NMR and ¹³C NMR spectroscopy. Essential oil extracts were analysed by GC/MS leading to the identification of 60 components. Sesquiterpene hydrocarbons accounted for the major make up of the oil. Microbiological screenings of the oil and successive plant fractions were performed, showing promising activity against a number of microorganisms with Minimum inhibitory concentrations (MIC) comparable to the standard antibiotics such as chloramphenicol and kanamycin. The plant ethanol extract (400 mg/kg) and the isolated coumarins (60 mg/kg) showed anticoagulant activity. Analyses to determine the activity of the extracts on liver and kidney function were performed, revealing no negative or detrimental effects.