The leaf samples of teak clones showing resistance or susceptibility to teak defoliator, Hyblaea puera Cramer under laboratory condition were analyzed for biochemical constituents viz., total phenols, nitrogen and potassium. The phenol content among the selected leaves of resistant clones varied from 0.56 to 1.43 per cent. Teak clones recorded gradual increase in phenol content in relation to increase in degree of resistance. The increased per cent nitrogen content recorded increase in the degree of susceptibility. There was no appreciable difference observed among the resistant categories of the teak clones with respect to per cent nitrogen content. The most resistant clone STG-3 and MYHAK-2, of state graft and Haliyal, respectively exhibited highest amount of potassium content (1.73%) as compared to others.