To optimize crop load of mangosteen, fruit density and leaf number: fruit were assessed using a framework of quadrat cube (0.5 x 0.5 x 0.5 m) in 2 consecutive years (2004-2005). Twenty-four 14-year-old uniform trees, field grown at Songkhla province, were selected to arrange 4 levels of crop loads: 1) Extremely low crop load (T1) = 264±5 fruit pt-1, 2) Low crop load (T2) = 826±36 fruit pt-1, 3) Medium crop load (T3 ) = 1190±27 fruit pt-1 and 4) High crop load (T4) = 1719±36 fruit pt-1. By placing the quadrat cube on the tree canopy, leaves quadrat-1 and fruits quadrat-1 were counted. Relationship between fruits quadrat-1 and fruit number pt-1 was found, and leaf number: fruit was also related to fruit yield pt-1. These results indicate that the assessment of fruit density and leaf number: fruit is of benefit for crop load management. Thus, 9 fruits quadrat-1 and 18 leaves: fruit are recommended to optimize crop load of mangosteen.