Cytological effects of three growth substances namely, Gibberellic acid (GA), Indole-butyric acid (IBA), and 2, 4-Dichlorophenoxyacetic acid (2, 4-D) were studied on root tip mitosis of Vicia faba treated with 10 and 50 ppm concentrations and 3, 6 and 12 hours durations. GA enhanced cell division while 2, 4-D and IBA inhibited it and were more toxic than GA. Main effects at chromosomal level were chromosome breakage, bridge formation, C-mitosis, micronuclei formation, stickiness and chromosome condensation.