Terpinolene (TPO) is a monocyclic monoterpene found in the essential oils of various fir and pine species. Recent reports indicated that several monoterpenes could exhibit antioxidant effects in both human and animal experimental models. However, so far, the nature and/or biological roles of TPO have not been elucidated in human models yet. The aim of this study was to investigate the genetic, oxidative and cytotoxic effects of TPO in cultured human blood cells (n = 5) for the first time. Human blood cells were treated with TPO (0-200 mg/L) for 24 and 48 h, and then cytotoxicity was detected by lactate dehydrogenase (LDH) release and [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (MTT) assay, while DNA damage was also analyzed by micronucleus assay, sister chromatid exchanges assay and 8-oxo-2-deoxyguanosine (8-OH-dG) level. In addition, biochemical parameters [total antioxidant capacity (TAC) and total oxidative stress (TOS)] were examined to determine oxidative effects. The results of LDH and MTT assays showed that TPO (at concentrations greater than 100 mg/L) decreased cell viability. In our in vitro test systems, it was observed that TPO had no genotoxicity on human lymphocytes. Again, TPO (at 10, 25, 50 and 75 mg/L) treatment caused statistically important (p < 0.05) increases of TAC levels in human lymphocytes without changing TOS levels. In conclusion, TPO can be a new resource of therapeutics as recognized in this study with its non-genotoxic and antioxidant features.