In Jiroft region, potato tubers keep in store and cold room in summer. During 2001-2002, several stores were surveyed in order to etiological study of potato tuber that exhibited either soft or dry rot symptoms. Infected tubers washed with water and disinfested with 1% sodium hypochlorite and then plated on PDA, WA and CMA edia. Also samples that showed soft rots cultured on NA, NAS and EMB bacteriological media. Pathogenicity tests carried out on health tubers of Primir cultivar by common plant pathological methods. At last, Cylindrocarpon didymum, Fusarium equiseti, Fusarium culmorum, Fusarium solani and Ralstonia solanacearum identified as causal agents of potato tuber rot in Jiroft with 56.4, 17.9, 12.8, 7.7 and 15.4 percent respectively.