Biochemical basis of disease resistance in oil seed crop (Sesamum indicum) after the attack of Tiarosporella phaseolina, a root rot disease causing pathogen was investigated. In order to determine whether phytoalexins are produced and play an important role in disease resistance induced by Tiarosporella phaseolina in Sesamum indicum, seven and fifteen days old plants were inoculated with the spores of the above said pathogen. It is evident from the results obtained that plant resistance to disease is usually the result of several factors. Plant resistance responds with an increase in polyphenols content accompanied by the rise in PAL activity, which is closely associated with the increase in the total protein contents. Total protein content increase in inoculated plants is accepted as obvious which include the synthesis and accumulation of pathogenesis related proteins (PRPs).