Acute lymphocytic leukemia (ALL) is a type of childhood leukemia with the highest incidence; T-acute lymphocytic leukemia (T-ALL) is far more difficult to treat than B-acute lymphocytic leukemia (B-ALL) and has a poor long-term prognosis. Therefore, there is an urgent requirement to develop effective drugs for the treatment of T-ALL. Hirsutanol A is a natural sesquiterpenoid compound. The aim of the present study was to evaluate the in vitro anticancer activity of hirsutanol A against T-acute lymphocytic leukemia Jurkat cells and investigate the mechanism of action. A Cell Counting Kit-8 assay demonstrated that hirsutanol A inhibited the viability of Jurkat cells in a dose- and time-dependent manner. In addition, hirsutanol A induced cell cycle arrest at the G2 phase as determined via flow cytometry. Furthermore, Hoechst staining, Annexin V-FITC/propidium iodide double staining, mitochondrial membrane potential detection using JC-1 and western blot analysis of apoptotic proteins indicated that the inhibitory effect of hirsutanol A on Jurkat cells was associated with the induction of apoptosis. Of note, hirsutanol A induced the expression of the tumor suppressor p53, whereas simultaneous treatment with pifithrin-α, an inhibitor of p53, significantly reduced Jurkat cell apoptosis induced by hirsutanol A. In summary, the present study suggested that hirsutanol A inhibited Jurkat cell viability through induction of cell cycle arrest and p53-dependent initiation of apoptosis, thus hirsutanol may serve as a promising compound for the treatment of T-ALL.Keywords: T-acute lymphocytic leukemia; apoptosis; hirsutanol A; p53.