The present work is focused on the study of the characteristics of the fruits of four main lemon (Citrus limon L. Burm.) varieties cultivated in Sicily: ‘Femminello Comune’, ‘Monachello’, ‘Zagara Bianca’, and ‘Femminello Santa Teresa’. Physical and chemical properties as well as aroma compounds were analysed as quality discrimination factors. Also the effect of the storage conditions was verified. Standard experimental techniques were used to determine: weight, longitudinal and transverse diameters, pH, titratable acidity, total soluble solids, juice percentage and total polyphenols. The volatile component was analysed by i) a gas chromatographer with a mass spectrometer detector and ii) an electronic olfactory system (“e-nose”) equipped with an array of six MOS sensors. Most of the physical and chemical parameters analysed allowed a statistically significant discrimination among the factors cultivar and storage time. The aromatic pattern was similar for all the cultivars. Differences were observed after the storage at 18°C, particularly for the cultivar ‘Monachello’.