The essential oils of the aerial parts ofCunila angustifolia, collected in two different regions in the southern Brazilian state of Santa Catarina, were analyzed by GC, GC/MS and13C-NMR spectroscopy. The main compounds in sample A were found to be sabinene (41.4%), γ-terpinene (11.3%) and limonene (9–5%). In sample B, trans-piperitone oxide (42.4%), sabinene (12.1%) and limonene (10.4%) were the main constituents. For confirmation of trans-piperitone oxide, the compound has been isolated by column chromatography and the structure established by spectroscopical methods.