A significant number of β-triketones have been reported from Australian Myrtaceae (1,2). We publish here the mass spectra of ten of these compounds (Figures 1-10). The source of the compounds is given below: Agglomerone - Eucalyptus agglomerata Maiden (1) Angustione - Backhousia angustqolia F. Muell. (1,3) Dehydroangustione - Backhousia angustqolia F. Muell. (1,3) Flavesone - Eucalyptus grandis W. Hill ex Maiden (4) Grandiflorone - Lqtospennum mrrisonii J. Thompson (unpublished source, 1) Leptospermone - Eucalyptus grandis W. Hill ex Maiden (4) Papuanone - Eucalyptus papuana F. Muell. (4) Platyphyllol - Melaleuca cajuputi Powell subsp. platyphylla. (3) Tasmanone - Eucalyptus cloeziana F. Muell. (2) Xanthostemone - Xanthostemon oppisiti$olius F. M. Bailey (1) AU spectra were recorded under E.I. conditions at 70 eV on aVG Quattro mass spectrometer during GUMS opention. The column used was a DB-5 (30 m x 0.32 mm) with helium as carrier gas.