Essential oil from Cochlospermum regium (Schrank) Pilg. leaves (CR-EO) has been extracted by hydrodistillation; we analysed the CR-EO by gas chromatography coupled with mass spectrometry. We also conducted histochemical analysis on cross-sections of the central vein of young and adult leaves. A total of 32 compounds were qualitatively and quantitatively analysed, which represented 94.87% of the total CR-EO oil content. The CR-EO basically consisted of sesquiterpenes (96.87%); its main component was beta-copaen-4-alpha-ol (18.73%), followed by viridiflorol (12.67%). The histochemical analyses identified the main classes of compounds present in both young and adult leaves.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)