Three peanut varieties namely Giza 6, Giza 5 and Grgury and four peanut genotypes (China, Zambia, Israil and Maxic) were tested for their resistance to root rot disease under greenhouse and field conditions in soil infested with Fusarium solani and Macrophomina phaseolina. Giza-5 was highly susceptible to these fungi gave the highest percentage of infection whereas Giza-6 was moderately susceptible but Grgury was moderately resistant . The four genotypes recorded ranges between moderately resistant and moderately susceptible. The free amino acids, soluble proteins, soluble sugars , water content and photosynthetic pigments were mostly higher in healthy plants than in infected ones and in the resistant peanut varieties or genotypes than the susceptible ones. Histological study as response of plants to fungal infections induced structural defenses. The stem anatomical characters such as secondary and primary xylem areas, phloem areas, the secondary fibers between the vascular bundles and whole vascular bundles area were represented. The cambium layer reduced in infected plants compared to uninfected plants. The larger xylem area was noticed in Grgury stems The largest phloem and whole vascular bundles areas were in Giza 6. Proportioning the secondary xylem length of the roots in percentages to the whole section radius revealed a unique behavior of Grgury while the minimum percentage was for Giza 5. Also, Grgury showed higher xylem vessels thickness than the others