The effects of different methanol extracts of Convolvulus arvensis on phytohormones (indole acetic acid (IAA), gibberellic acid (GA), abscisic acid (ABA) and salicylic acid (SA)) levels of corn were investigated. It was observed that all concentrations of methanol extracts (50 µl, 75 µl, 100 µl) of roots, stems and leaves of C. arvensis decreased the mitotic index and also caused abnormalities in chromosomes. On the other hand, phytohormone levels have been changed by application of different extracts at various concentrations. Compared with the control, GA levels decreased significantly whereas ABA levels increased in all the application groups. SA and IAA levels showed changes depending upon applied extracts and their concentrations.