The success of commercial banks is dependent on their ability to manage loan funds issued to its customers. Despite strategies implemented, banks do experience loss due to non-performing loans (NPLs). The purpose of this research was to investigate factors influencing NPLs in Tanzanian Banking Industry - A case of selected commercial banks in Mwanza city. The study was further guided by three specific a research objectives „(i) to determine the level of non-performing loans at the selected commercial banks in Mwanza city, (ii) to identify bank specific factors that affect non-performing loans at the selected commercial banks in Mwanza city and (iii) to determine some of the remedial practices can be implemented to reduce the level of non-performing loans at the selected commercial banks in Mwanza city. The research surveyed 59 loan officers from two selected commercial banks in Mwanza city using a self administered structured questionnaire. Personal interviews were also held with some selected managers and loan officers from those selected commercial banks. The results from the study indicated that commercial banks in Mwanza city have experienced over 50% of their loans as NPLs and these have been increasing over the period of 2013/2014 to 2017/2018. The study further found that macro-economic factors, customer related factors and bank related factors were responsible for high percentage of NPLs. To address this problem, the study found that bank have instituted some measures such as monitoring system and risk management strategies but have not been that effective in reducing levels of NPLs. The study recommended among other things, that implementing a more strict loan payment procedures, strict loan application evaluation process, making collateral as mandatory requirement for all loan applicants and training loan officers on best practices of credit appraisal and risk management as well as training customers on loan repayment procedures.