In this study, the genotoxic effects of the herbicide Quizalofop-p-ethyl (QPE) on the root meristem cells of sunflowers (Helianthus annuus) were investigated. In the sunflower root growth tests, the effective concentration (EC50) value was determined as approximately 1.5 mg/L. The roots were treated with 0.75 (EC50/2), 1.5 (EC50), and 3 mg/L (EC50 x2) concentrations of Quizalofop-p-ethyl for 24, 36, and 48 h, with a control for each combination. The occurring morphological changes in the sunflower roots with the herbicide concentrations were monitored. The mitotic index and mitotic abnormalities were determined in both the control and test groups. The mitotic index decreased with the increase in the herbicide concentration at each exposure time. The mitotic abnormalities were recorded as disturbed prophase, c-mitosis, stickiness, laggard chromosomes, and chromatid bridges. The micronucleus was observed at interphase and its frequency was calculated in the different test solutions.