Male florets and pistillate flowers of cvs.Chandler and Hartley of Persian walnut were cultured on modified Murashige and Skoog medium (MS) supplemented with 0.05 mg l-1 biotin, 0.5 mg l-1 folic acid, 100 mg l-1 glutamine and different concentrations of Naphthalene acetic acid (NAA) and Kinetin (KIN) and for pistillate flowers culture, these concentrations were 0.25, 0.5, 1 and 2 mg l-1). After four weeks, the percentage of callogenesis of male florets in cv. Chandler was more than cv. Hartley. In the sixth and tenth weeks, the rate of callogenesis of male florets was depended on cultivars, the ratio of NAA: KIN and interaction between them; so in the sixth week, the highest rate of callogenesis was obtained in the higher ratio of NAA: KIN. In the tenth week, the effect of cultivars was not significant and the highest rate of callogenes is of male florets was obtained in treatments 4 (2.5 mg l-1 NAA with 1.25 mg l-1 KIN), 5 (1.25 mg l-1 NAA with 1.25 mg l-1 KIN), 7 (2.5 mg l-1 NAA with 0.5 mg l-1 KIN) and 8 (1.25 mg l-1NAA with 0.5 mg l-1 KIN) of cv. Chandler. By culturing pistillate flowers on modified MS medium, nodular compact calli formed on the upper and lower part of flowers. During the next weeks, callogenesis occurred in sepals and leaflets of pistillate flowers and then stigmas and styles swelled and formed nodular calli. Similar to male florets, the rate of callogenesis in pistillate flowers depended on cultivars, the ratio of NAA: KIN and interaction between them.In the sixth and tenth weeks, the highest rate of callogenesis of cv. Chandler pistillate flowers was obtained in treatments including high or same concentrations of NAA: KIN. Callogenesis of pistillate flowers of cv. Hartley was achieved from different ratios of NAA: KIN. The lowest rate of callogenesis in the sixth and tenth weeks was obtained in the low concentrations of NAA and KIN. With increase of callogenesis in treatments 3 (0.5 mg l-1 NAA with 2 mg l-1 KIN), 6 (1 mg l-1 NAA with 1 mg l-1 KIN), 10 (1 mg l-1 NAA with 0.5 mg l-1 KIN), 11 (0.5 mg l-1 NAA with 0.5 mg l-1 KIN), 12 (0.25 mg l-1 NAA with 0.5 mg l-1 KIN), 14 (1 mg l-1 NAA with 0.25 mg l-1 KIN), 15 (0.5 mg l-1 NAA with 0.25 mg l-1 KIN) and 16 (0.25 mg l-1 NAA with 0.25 mg l-1 KIN) of cv. Chandler and treatments 9 (2 mg l-1 NAA with 0.5 mg l-1 KIN) and 11 (0.5 mg l-1 NAA with 0.5 mg l-1 KIN) of cv. Hartley, the tissues of pistillate flowers turned into masses of nodular calli similar to embryogenic ones.