Cold-pressing and hydrodistilled peel oils of two Brazilian mandarin cultivars, commonly called Cai and Montenegrina (Citrus deliciosa Tenore), were obtained from fruits collected on mandarin trees submitted to the same pedoclimatic and cultural conditions. Their chemical composition and seasonal variation of the main volatile constituents were investigated by capillary GC and GC-MS, and the results were submitted to statistical analysis. To better characterize the oils, the enantiomeric distribution ratio of seven components (alpha-pinene, sabinene, beta-pinene, limonene, linalool, terpinen-4-ol, and alpha-terpineol) was determined by multidimensional gas chromatography (MDGC). The similarities found between both C. deliciosa cultivars are strong evidence for the hypothesis that Montenegrina originated from Cai as previously reported from agronomic studies.