Marrubium vulgare L. (Lamiaceae) is a herbal drug used for centuries for many diseases. In this present study the plant material was acquired from commercial sources in pharma grade (PhEur 8.0) quality. The methanol extract of the aerial parts was evaluated for its in vitro cytotoxic activity by measuring the percentage of viable cells (U87 LN229 and T98G glioblastoma multiforme cell lines) using a luminescence system, and the antioxidant activities by ABTS and DPPH radical scavenging spectrophotometrically. As a result, the methanol extract of M. vulgare showed 48.97 ± 0.82 mg of GA/g corresponding to the total phenolic amounts, and moderate antioxidant activity (1.33 and 2.08) by ABTS • and DPPH • assays. To the best of knowledge, after evaluation of the cytotoxicity on M. vulgare treated U87 (IC50:270.3 μM), LN229 (IC50:343.9 μM) and T98G (336.6 μM) glioblastoma multiforme (GBM) cell lines, significant cytotoxic activities with 69.9% (p= 0.0081) and 71% cell viability (p= 0.0028) was observed in M. vulgare treated U87 and LN229 GBM cell lines, respectively. Overall, further in vitro and in vivo bioactivity studies based on phytochemistry on various M. vulgare preparations are worthwhile in order to discover bioactive secondary metabolites.