Rubber is one of the major plantation crops cultivated in Kerala. In Kottayam district, the competition between rubber and coconut is maximum. A study was conducted in 1998 March in Meenachil and Kottayam taluks of Kottayam district, in order to out the peak bearings age and optimum replacement age of rubber plantations. Although the farmers are not aware about the losses incurred by them, by keeping the plantation year after year, studies regarding this aspects are lacking in this crop in order to make them aware of the replacement age. Here the peak bearing age was identified as the 21st year, by fitting a quadratic regression by taking age and age was variables keeping the input and labour cost constant. Similarly, optimum replacement age 2 as calculated by finding out the annuities. The year at which the annuity attained a peak will be optimum replacement age. Hence it is identified as the 29th year. Therefore replacement should be effected at the 29th year.