Provided are a method, system, and article of manufacture for assigning alias addresses to base addresses. An assignment is provided of base addresses to the devices. The base addresses are used to access the devices assigned to the base addresses. An assignment is provided of a plurality of alias addresses to an alias address pool. The alias addresses in the alias address pool are capable of being dynamically assigned to the devices to service I/O requests to the devices. An Input/Output (I/O) request to access one target device comprising one of the devices is processed. A determination is made as to whether the base address assigned to the target device is available. One alias address is assigned to the target device in response to determining that the base address is not available. The I/O request is issued to the assigned alias address to transmit the request to the target device.