Studies on the response of mature rubber(Hevea brasiliensis Mud, Arg, clone RRIM 600) to different levels of potassium (K) application in a laterite soil in the low available (morgan extractable) K status showed an increase in the volume of latex and dry rubber yield with K application upto 600 kg/ha-1. Dry rubber content was not influence by potassium application. Linear, quadratic and cubic response models were fitted for the rate of K supply and the mean annual volume of latex and dry rubber yield. The response was similar during all the three years of study, but treatment differences gradually narrowed in the second and third year. There was a positive correlation between K application and available K status in the soil and K concentration in the leaf.