The essential oil (EO) of M. aquatica L. growing wild in Corsica was isolated by dry vapor distillation and submitted to combined analysis by column chromatography over silica gel, CG(RI), GC-MS and 13C NMR spectroscopy. The composition was dominated by oxygenated monoterpenes and characterized by the occurrence of menthofuran (50.7%) as major component. In parallel, seven laboratory-distilled oil samples isolated from individual plants collected in Corsica were analyzed by GC(RI) and 13C NMR spectroscopy. Only quantitative differences were observed within the samples. Beside usual terpenes, various p-menthane lactones (mintlactone, isomintlactone, hydroxymintlactone, menthofurolactone and epimenthofurolactone) have been identified in all oil samples.