Cantaloupe plants became increasingly suffer from sudden wilt disease caused by Monosporascus cannonballus. This disease start to appear on plants at fruit set stage. The present study was aimed to find out biochemical marker could be differentiate between resistant and susceptible plants to this disease. The attention was focused on protein marker. Soluble protein was extracted from healthy and diseased plant roots as well as from 16^th leaf of diseased and healthy ones. Moreover, protein of cantaloupe seeds was also extracted. Protein extraction was subjected to SDS-electrophoresis. Band with M.W 72.08 K.Da was found only in healthy roots, and a band with M.W 25.31 K.Da was found in healthy plant leaves and absent from diseased ones. From seeds band with M.W 25.66 K.Da was found in 50% of cantaloupe seeds (Galia hybrid). This protein marker would be useful for selection of transplants for cultivation.