Abstract: The present research was aimed to investigate whether Nitric Oxide (NO) is involved in zinc homeostasis in plants. It also aimed to study the involvement of GSH, SH groups and NO in mediating changes in zinc homeostasis. Wheat seeds (Triticum aestivum L., Cultivar giza-167) and bean seeds (Phaseolus vulgaris, cultivar Bronco) were germinated and grown in vermiculite watered with nutrient solution. Zinc was supplied in different concentrations (0.5, 2.7, 5.4 (control), 10.8 and 21.6 μM as ZnSO4). Sodium Nitroprusside (SNP) was used as NO donors in a 100 μM concentration and Methylene Blue (MB), in a 100 μM concentration, was used as NO scavengers. The solutions were supplied to plants by irrigation once a week included in the nutrient solution. 21-d-old plants were harvested. The results revealed that SNP application (NO donor) alleviated the adverse effect of deficient and toxic levels of zinc concentrations by increasing shoot and root biomass allocation, RGI% and protein content. Moreover, SNP application maintains a suitable zinc concentration in both deficient and toxic levels of zinc supplies in both wheat and bean seedlings. Nitric oxide induced significant changes in total and free/total SH, GSH content and SOD activity. The effect of nitric oxide was supported by using MB which scavenges the endogenous nitric oxide. The effect of NO is suggested to be a result of the adjustment of total or free SH levels, glutathione content and SOD activity.