We report the applicability of Hypoxanthine Guanine Phosphoribosyl Transferase (HGPRT) gene to test the potential mutagenic activity of Teucrium apollinis (TA). Genotoxicity of low dose (LD) 50µl and high dose (HD) 250µl of fixed oil extracted from TA were examined using asexual cell (oidia) of Coprinopsis cinerea. Surprisingly, survival of wild type cells was significantly decreased to 45.8 and 29.3% when oidia incubated with LD and HD respectively illustrating its cytotoxic effect. Mutation rate decreased to 0.33 and 0.4 with selected doses of the plant extract correspondingly which means that both were mutagenic. DNA damage of Coprinopsis cinerea were also quantified by spectrophotometer. There were significant differences (LSD= 0.05) between negative control and treatments, since the highest value was 94.33±2.41µg/ml in control, the lowest amount of DNA (32.53±3.40) obtained when hypha treated with positive control (MSG). Unsurprisingly, LD and HD reduced DNA values to 33.84±3.26 and 31.56±2.70 correspondingly, indicating the genotoxicity of TA concentrations. Ten components were identified by GC-MS of the oil extract involving Camphor and Furanone. Thus cytotoxic and mutagenic of medicinal plants must be assessed to ensure a relatively save use for our important population.