Indigenous microorganisms (IMO) have great potential in agricultural uses since they have high ability in biodegradation, nitrogen fixation, phosphate solubilization, plant growth hormone production. However, deep scientific knowledge about IMO's growth-promoting effect and vegetable yield has been limited and should be elucidated. This study aimed to evaluate the effect of some selected IMOs on the growth, yield of water spinach under greenhouse and field conditions. The greenhouse experiment was carried out with water spinach seeds that were inoculated with IMO solution at a dilution of 1.000-fold for 4 h and grown for 26-30 days. The level of chemical nitrogen fertilizer dose application for pot experiments were 25% recommended N and 50% recommended N. The field experiments were arranged in the condition that water spinach seeds were soaked in 500 times diluted IMO solution and reduced by 25% the amount of nitrogen fertilizer recommended for water spinach. The result showed that IMO helped to reduce 25% chemical N fertilizer, increase water spinach yield up to 18% as well as reduce from 42 to 59% of the total nitrate in fresh vegetables as compared to the control fertilizer recommended treatment. It is possible to exploit indigenous microorganisms as a source of beneficial microorganisms for stimulating plant growth and increasing vegetable yield.