Although several studies show that Schinus terebinthifolius Raddi fruits are a promising source of bioactive compounds, few studies have investigated the anticancer activity of its essential oil (EO). The objective of this study was therefore to investigate the antiproliferative activity of S. terebinthifolius fruit EO against eight human tumor cell lines. A central composite rotatable design with 11 experiments was developed to investigate the optimal conditions of hydrodistillation by Clevenger apparatus. EO obtained at optimized conditions (yield greater than 6.7%) showed potent activity for all cell lines investigated; the most promising results were observed against leukemia, kidney, multidrug-resistant ovarian, and prostate tumor cell lines. Gas chromatography-mass spectrometry revealed the following major compounds in the EO: delta-3-carene (33.78-36.73%), alpha-phellandrene (15.67-17.30%), limonene (15.03-16.32%), alpha-pinene (7.03-9.20%), and germacrene D (4.98-6.99%). Future work involving fractionation of the EO might shed some light on the compounds responsible for each antiproliferative activity.