Background and objectives: Iran owns a rich and prestigious heritage of medicinal herbs but the majority of these plants have not yet undergone chemical, pharmacological and toxicological studies. In the present study some species form northern parts of Iran were evaluated for cytotoxicity. Methods: Sixteen medicinal plants were extracted with methanol and screened for their cytotoxic activities. The inhibition of cell growth for these extracts was evaluated against MCF-7, WEHI-164, HepG-2 and MDBK cell lines. Their 50% inhibitions of growth (IC50) were determined by MTT assay. Moreover, cytotoxic evaluation of different fractions of the most potent species was performed. Results:Among examined samples, the IC50 values of methanol extract of Centaurea bruguierana (DC.) Hand.-Mzt. on mentioned cell lines were found 47.30-87.40 µg/mL. In addition, the chloroform fraction of the species was cytotoxic with IC50 values 17.00-23.03 µg/mL. Conclusion: It was concluded that the chloroform fraction of C. bruguierana was the best candidate for identification and isolation of active principles with cytotoxic effects. These results recommend further studies about this species.