Abstract The leaf oil of Mentha grandiflora Benth. contained trans-piperitone oxide (21%), piperitenone oxide (36%), pulegone (19%) and menthone (10%) as principal components. The oil yield was 1.5% (based on fresh leaves). Key Word Index: Mentha grandiflora Lamiaceaeessential oil composition trans-piperitone oxidepiperitenone oxidepulegonementhone