Leaf from two Guatteria elliptica R. E. Fries (Annonaceae) specimens were collected at Paranapiacaba and Caraguatatuba in São Paulo (Brazil). The essential oils presented (GC/GC-MS), as major compound, spathulenol (53.9%) for the Paranapiacaba specimen and caryophyllene oxide (40.9%) for Caraguatatuba. The oils showed low antioxidant activity with EC50 = 7.24 ± 1.03 and 28.68 ± 5.78 mg/mL, respectively, for Paranapiacaba and Caraguatatuba specimens. Both oils did not show a relevant (MIC > 3 mg/mL) antimicrobial activity. However, the Paranapiacaba oil presented an important antitumour activity against breast and prostate cancer cells (IC50 = 7.01 ± 0.23 and 5.35 ± 0.35 μg/mL, respectively) and a low cytotoxicity against normal fibroblast cells (IC50 > 22.27 e IC10 = 18.55 ± 1.89 μg/mL). Isolated major compound, spathulenol, showed good activity against MCF-7 and PC-3 with IC50 = 5.38 ± 0.20 and 2.25 ± 0.28 μg/mL μg/mL, respectively.