Retail loans became an important instrument of banking during 1960s. The effect of retail loans, in which mortgage and consumer loans have a great share, in the profitability of banks has not been analyzed in detail so far. The main items of retail loans, like mortgage and consumer loans, contribute greatly to the risk management of banks with their characteristics like having regular cash flow in banks. Due to the structure of the guarantee and mortgage loans, which provides low risk weight, it is important to determine the capital needs of banks. However, due to relatively long maturity structure, mortgage loans also feed the maturity mismatch risk, which is the basic problem of banking system. Such loans, with which low costs are provided in favor of the clients, play a considerable role in the profitability of banks. Consumer loans, on the other hand, are provided to the clients in shorter maturity periods and with costs that are more in favor of banks. In the scope of this study, the effects of retail loans on conventional banks and participation banks, which are active in Turkey, have been investigated for mortgage and consumer loans. The findings of the study show that retail loan types have strong negative effects on Net Interest Margin (NIM), which has been selected as the profitability indicator for conventional banks in the scope of the study. For Participation Banks, on the other hand, unlike conventional banks, retail loan types have stronger and more positive influences on Net Profit Share Margin (NPSM). The findings of the present study are important for further studies that will be conducted on retail banking and for comparative studies on performance assessment.