Purpose: Cancer is a long process that leads the organism to death and is associated with the normal cells acquiring the ability to divide permanently. Nowadays, the use of natural products in cancer therapy has a great importance. In addition, working with plants that are endemic to Turkey and determining the biological activities of these plant extracts, is extremely important due to the potential for new drug development. There is no comparative study available in the literature on the antitumor effects of Colchicum sanguicolle, a new found species of the genus Colchicum in Turkey, Crateagus microphylla, of the genus Crateagus and Centaurea antiochia of the genus Centaurea. In this study, we tried to demonstrate the antitumor effect of these plant extracts on HeLa and C 4-1 cells.