A two - year Invetigation (1997-98) was conducted to determine the various losses of potato tubers after harvesting and during the storage periods. The results revealed that 23.02 percent of the harvested tuber go on waste due to various causing effects including diseases and / or evironment. The components of these losses individually were of soft rot 3.43%, Fusarium dry rot 4.89%, Brown rot 2.30%, tuber greening 2.44% internal bruising 1.27%, physiological disorders 4.38% (includings cracking, unsuitable harvesting, secondry growth, under sized of tubers, etc.) deep injuries due to unsuitable harvesting, 1.72% and pests including Gryllotapa gryllotapa, Agrotis lineatus and phethrimea aperculella totally 1.65%. Statistical analysis showed no any significant effects in years but there was of a high correlation coefficient. The potato cultivars were cosima, marfona,Morren, Agria, Pikaso, Deraga and Arrian. The loss of potato tubers in these cultivars were 25.66, 24.76, 23.34, 21.24, 20.50, 18.56 and 17.20 percent, respectively. Potato cultivars differed in their degree of losses to various causing agents and/or effects in totality in which there were of a significant effects between the cultivars as far as the individual causing effects are concerned. Diseases such as black scurf (Rhizoctonia solani) and scab (Streptomyces scabis) were not enocunted, because of no any potato losses but there are losses in marketing. The other very minor diseases and environment effects were not included too.