Introduction: The cytotoxic effects of Ferula assafoetida extract intensely depend on highquality extraction. The type of solvent used is a critical parameter for efficient extraction in the maceration method. In the present study, the phytochemical and cytotoxic effects of different Ferula assafoetida extracts were compared. Methods: The Ferula assafoetida gum was extracted using different polar solvents: hydroethanol (70% v/v), dimethyl sulfoxide (DMSO), and water. The phytochemical properties of the extracts were evaluated, focusing on their herbal content of phenols and flavonoids. The antioxidant activity of the extracts was also compared by assessing their radical scavenging capacity (by DPPH assay) and reducing activity (using the FRAP assay). Finally, the cytotox effects of the extracts were evaluated using the MTT assay on MCF-7 and MDA-MB-231 breast cancer cell lines for the first time. Results: The phytochemical properties of hydroethanolic extract of Ferula assafoetida (HEFA) were significantly (P< 0.0001) higher than those of the DMSO (DEFA) and water extracts (WEFA). The reducing power, radical scavenging activity, and cytotoxic effects of HEFA were also significantly (P< 0.05) higher than those of DEFA and WEFA. The cytotoxicity of the extracts was dose- and incubation time-dependent. HEFA exhibited the highest cell cytotoxicity at 72 hours, with IC50 values of 69.97± 9.45 µg/mL on the MCF-7 cell line and 60.22± 2.37 µg/mL on the MDA-MB-231 cell line. Conclusion: Hydroethanol was the best solvent for extracting phenolic compounds and flavonoids. The cytotoxic effects of HEFA were also the highest, probably due to the high ability of hydroethanol in the extraction of hydrophilic and lipophilic phenols.