This study investigated the effects of Arbuscular Mycorrhizal Fungi (AMF) and whey on the growth of potato (Solanum tuberosum L.) and Rhizoctonia solani disease. Experiments were carried out in a greenhouse with three different AMF applications (Glomus mossease, commercial AMF, mixed AMF), whey and Rhizoctonia solani AG-3. The study findings indicated that application of AMF and whey had positive effects on plant growth and that AMF development was enhanced by whey application. Growth components (plant height, shoot fresh and dry weights, root fresh and dry weights) increased significantly with AMF and whey application when compared to control as well as plants inoculated with R. solani alone. AMF and whey also significantly reduced the harmful effects of the disease. These applications reduced the severity of R. solani disease by between 40% and %53. Mixed AMF combined with whey had the best affinity in terms of both AMF colonization (73%) and mycorrhizal dependency (30,3). Combinations of two treatments were more effective than individual applications.