Cancer treatment using medicinal plants has long been of interest to researchers. In the meantime, some plant species contain substances which can inhibit or eliminate cancer cells through apoptosis or necrosis. The family of Lamiaceae and Asteraceae are among the medicinal plants that have many biological effects. The purpose of this study was to investigate the anticancer effect of Pennyroyal and Artemisia extracts on gastric cancer cell line (AGS). In this study, aerial parts of plants, Artemisia persica and  Mentha longifolia , were extracted. AGS cells were treated with different concentrations of hydro-alcoholic extract (50-1000 µg/ml) over 24, 48 and 72 hours. Cell motility was estimated using MTT assay and rate of apoptosis induction was measured by flow cytometry with The Annexin-V. The results of MTT assay indicated strong and concentration dependent prevention of cancer cell proliferation by various concentrations of Pennyroyal and Artemisia extracts. These extracts had a dose and time dependent anticancer effect on AGS cells. By increasing the concentration of the extract and incubation for 72 hours, the highest percentage of cell death was observed. In the study of apoptosis in treated cells, Pennyroyal extract was more effective. Due to the cytotoxic effects of hydro-alcoholic extracts on AGS cells, these plants could be used as potential option for further studies on cancer treatment. Therefore, the purification of the active substances in these extracts and the determination of their effect mechanism are recommended.