Biochemical studies were carried out on non-Bt genotypes Laxmi, Abhadita, DCH-32 and Bt genotypes RCH-2 Bt, JKCH-1 Bt, JKCH-2 Bt. All the test genotypes were found susceptible to the Grey mildew (Ramularia areola) disease. The results indicate that non-Bt genotypes recorded high amount of total protein (9.18 to 20.63%) but total phenol (-18.39 to- 22.07%), total sugar (-7.60 to -12.17%) and reducing sugar (-19.05 to -23.29%) recorded lower amount compared to Bt genotypes. High amount of non-reducing sugar (12.74%) content at early stage (90 DAS) and low amount (-27.04%) at later stage (120 DAS) compared to Bt genotypes. Further, the decrease in total protein (-28.38 to -30.40%), total phenol (26.40 to -33.90%), total sugar (-32.43 to -35.47%), reducing sugar (-21.19 to -37.58%) and non-reducing sugar (-34.21 to - 46.91%) was more in infected plants of Grey mildew disease.