Abstract: A shopping cart rental system for renting shopping carts and encouraging returning of shopping carts to designated areas. The shopping cart rental system includes a plurality of rental assemblies. Each of the rental assemblies comprises a housing. The housing comprises an upper portion. A lower portion is couplable to the upper portion. A plurality of coin slots are located on a front face of the upper portion. A key slot is formed through a rear face of said upper portion. A key is for inserting into the key slot. The key is coupled to the upper portion of the housing. A key retaining assembly is for retaining the key in the key slot. A coin operated assembly for actuating the key retaining assembly. The coin operated assembly is operationally coupled between the coin slot and the key slot.