A flow-actuated pressure equalization valve, for use with a downhole tool such as a treatment tool, for use in stimulating a subterranean formation. The equalization valve allows the pressure of treatment fluid above and below an isolation device to be equalized so the treatment tool can be moved. The valve can be closed when fluid flow exceeds a certain threshold and the treatment tool is set in the wellbore. While running in or pulling out of hole, the valve will not close regardless of the rate of fluid flow. The valve can be opened by stopping fluid flow and then bleeding off pressure above the isolation device, or by pulling up on the treatment tool.