This study was carried out to compare the effect of Trichoderma harzianum with two fungicides i.e. Bavistin 50 and Rovral 50 on healthy survival plants and yield compo¬nents of two watermelon cultivars namely Giza 1 and Improved paecock. Results showed that seed treatment with spores of T. harzianum, Bavistin 50 and Rovral 50 showed an increase in the percentage of survival plants compared with untreated one. Furthermore, treated seeds with spores of T. harzianum presented an increase more than those treated with fungicides. Also, seed treatment with T. harzianum, Bavistin 50 and Rovral 50 presented an increase for number of marketable fruits and average fruit weight per plot, fruit diameter except fruit rind-thickness and total soluble solids percen¬tage compared with untreated seeds. In this respect, T. harzianum reported good results compared with fungicides the two cultivars.