The volatiles of three Greek cucumber cultivars (Cucumis sativus L.) were analyzed by gas chromatography and mass spectrometric detection. Twenty-one components were identified. The major components from each sample were found to be: sample A, Z-6-nonenol (61.54%), E-2-nonenal (6.98%), sample B, E,Z-2,6-nonadienal (47.08%), E-2-nonenal (17.39%), Z-3-nonenol (14.79%), 3-nonenal (7.32%), sample C, pentadecanal (43.47%), 9,12,15-octadecatrienal (14.52%) and 9,17-octadecadienal (12.33%). Additionally, several constituents have been isolated and identified from the dichloromethane, and methanolic extract of fruits from sample B. It was found that cucumber contained a high concentration of L-(+) lactic acid which, as a member of a-hydroxy acids (AHAs) with established use in cosmetology, could explain the traditional use of cucumber in skin treatment. Finally, the in vitro antioxidant (DPPH [1,1-diphenyl-2-picrylhydrazyl] assay) and antimicrobial activity of the extracts and/or volatiles from all studied samples against six bacteria and three fungi were also assayed and reported.