The present study was conducted to investigate the effect of triazophos in tissue cultures of three plants Catharanthus roseus, Zizyphus vulgaris and Eucalyptus globulus. Triazophos was compared with 2,4-D on Murashige and Skoog's (MS) medium supplemented with different concentrations of them. Triazophos was tested for it is potential in callus induction and compared its activity with 2,4-D as plant growth regulator .There are no significant differences (p<0.05) in callus induction on leaf explants between Triazophos and 2,4-D of all plants. The best concentrations to initiation and maintenance callus were (0.1and 1) mg/L for Triazophos and 2,4-D respectively for all plants.