An improved system is disclosed for ensuring the integrity of data stored on a dispersed data storage network. Checksums are used to ensure integrity of both data segments and data slices. Checksums appended to data slices are checked by receiving slice servers to ensure that no errors occurred during transmission. Slice servers also periodically recalculate checksums for stored data slices to ensure that data slices have not been corrupted during storage. Checksums appended to data segments are checked when data segments are read from the storage network.