This paper presents the pathological and biochemical changes among the freshly harvested potato tubers, freshly harvested infected tubers, cold stored healthy tubers and cold stored rotted tubers. In the study, fresh and infected samples of potato tubers were taken from the farmer’s field to understand the pathological and biochemical diversity. After the examination, potatoes were kept in the cold storage and studied again for pathological and biochemical changes. The potatoes were found infected by the Alternaria solani fungus during the season and Aspergillus niger fungus after storage. Biochemical parameters like vitamin c, fat, starch, gallic acid, chlorophyll, xanthophylls, carotene except oxalic acid indicates the significant reduction in nutrients value in stored and infected potato tubers.