Integrated polarization of spiral galaxies can provide statistical information about magnetic field properties and Faraday rotation for large samples of spiral galaxies, and for galaxies at high redshift observable with the SKA. Principles of such an analysis are discussed for a sample of nearby spiral galaxies combined with models of synchrotron emission and Faraday rotation for disk galaxies. Observations and models show significant polarization of the integrated emission, in some cases more than 10% at 4.8 GHz. The models suggest that the polarization degree of the integrated radio emission of spiral galaxies is sensitive to the ratio of random to regular magnetic field if the inclination is less than 50 degrees. The observed polarization of the integrated emission is less for the more luminous galaxies in our sample, suggesting different conditions in large, luminous spiral galaxies. First results are presented of a survey with the Effelsberg telescope of integrated polarization of spiral galaxies throughout the Local Supercluster. These data provide a local comparison sample to study the cosmic evolution of magnetic fields in spiral galaxies with the SKA.