Controlling a rate of prefetching based on bus bandwidth. A determination is made as to whether a rate of prefetching data from memory into a cache is to be changed. This determination is based on bus utilization, and includes identifying a most utilized bus of a plurality of buses used for the prefetch of data, and monitoring utilization of the most utilized bus. The determination whether the rate of prefetching is to be changed is based on the monitoring. Based on determining that the rate is to be changed, the rate of prefetching is changed.