Abstarct: Among the greenhouse products of Iran, cucumber (Cucumis sativus L.) has the highest area of cultivation. Since almost of greenhouse cucumbers are gynoecious (female flowers), this study was investigated the effect of 1-methylcyclopropane and cobalt chloride in production of male flowers in Cucumis sativus var. Sarina. The germinated seeds of cucumber were planted in pots and the seedlings at the two true leaf stage of growth were sprayed using silver nitrate (50, 75 and 100 mg/l), cobalt chloride (10, 20 and 40 mg/l) and 1-MCP (1 and 2 mg/l). In this experiment, plant height, number of leaves in plant, stem diameter, leaf length, petiole diameter, leaf width, the number of male flowers, the number of female flowers and pollen grain germination were evaluated. The results showed that in all treatments, the number of female flowers of cucumber was lower than the control. The application of silver nitrate, cobalt chloride and 1-MCP had a positive effect on the exxpression of male flowers on cucumber plants compared to the control. Silver nitrate treatment (100 mg/l) caused the highest number of male flowers as a 4.77. In this study, the lowest number of male flowers produced in 40 mg/l cobalt chloride as well as 1 g/l 1-MCP and 50 mg/l silver nitrate. The highest pollen grain germination was observed in all concentration of silver nitrate (84%).