Greenhouse and field experiments were carried out in sandy soil at the Ismailia Agricultural Experiment Research Station to determine the effect of five soil amendments on the yield and disease incidence in two peanut cultivars (Gregory and Giza 6). The results indicated that the Gregory cultivar significantly surpassed Giza 6 regarding plant growth parameters, yield and yield components. It was also less susceptible to pre- and post-emergence damping-off and nematode infection in two testing seasons. Adding gypsum increased plant height, number of branches/plant, 100-seed weight, shelling percentage, pod weight and oil yield followed by farmyard manure and wheat straw for most of these characters. Fusarium spp., Macrophomina phaseolina, Rhizoctonia solani; Sclerotium rolfsk Aspergiius spp., Pythlum spp. and Meloidogyne spp. were isolated from peanut cultivated at the Ismailia Agric Res. Station. Amending soil with gypsum gave the highest reduction of F. solani, M. phaseolina, R. solani and 5. rolfsii incidence, damped-off seedlings and rotted pods in the greenhouse. Also, gypsum was the most effective treatment in the field experiments reducing the pre-, post-emergence damping-off, pod rots and nematode infections in both cultivars in the two seasons. There was a significant interaction between peanut cultivars and treatments in six out of eleven studied characters in their combined data. Key words: soil amendments, peanut, damping-off, pod rots