PEANUT (Arachis hypogaea L.) is an important leguminous crop in Egypt. Root rot caused by Rhizoctonia solani is the most common disease of peanuts. In this study, six isolates of R. solani were isolated from peanut roots in El-Behera governorate during 2014 and 2015 growing seasons. Humic acid (H), sulfur (S) and gypsum (G) alone or in combinations were used as a seed dressing or a soil application to control root-rot disease in two peanut cultivars (Gregory and Ismailia1). Results indicated that peanut cv. Gregory appeared to be more susceptible to the fungus than cv. Ismailia1. Under greenhouse conditions, the combination of the three substances (H+S+G) caused the highest reduction in the incidence of R. solani damping-off on peanut cv. Gregory. Similar results were also obtained in the field experiment during 2015 and 2016 growing seasons. Furthermore, the results also indicated that each chemical substances and their combinations improved the growth characters in terms of the root and shoot weight as well as the yield of peanut plants.