The present investigation was carried out during the two successive seasons of 1998 and 1999 to compare the effect of spraying indole acetic acid (IAA) at the rates of 0,5 and 10 ppm on yield of four mungbean cultivars; V-2010, VC-1000, VC-2719 and Kawmi-1. Two samples were collected 7 days after each spraying treatment (42 and 62 days after sowing).                 It was found that IAA at 5 ppm increased leaf area and total dry weight of all cultivars. However, plant height and No. of leaves and branches were not varied with IAA at 10 ppm among all cultivars, except VC-1000.  At harvesting, the results indicated that the plants treated with concentration of 5 ppm gave better values of yield and its components than the control. At 10 ppm IAA level, no significant differences in yield and its components of VC-2719 and and VC-1000 cultivars were observed. Photomicrograph of the anatomical observations of Kawmi-1 and VC-1000 cultivars revealed that plants treated with 5 ppm IAA and/or 10 ppm treatments gave the highest values for stem and leaf measurements as compared with the control.                                 This increase in growth and yield is considered to have been caused by the increase in the chemical components; sugars, total free amino acids,N, P, K, Na, Fe, B, Cu and Zn , as well as phytohormones (IAA, GA₃ and ABA) concentrations.                 It could be concluded that IAA treatments enhanced harvesting  of mungbean plants through its effect on increasing  vegetative growth, and stimulative flowering process or improving yield and its components,