In order to give a good description of the polarization properties of extragalactic radio sources together with some other radio and optical data for these sources, all published polarization observations of extragalactic radio sources from 1965 to the middle of 1974 have been collected. After applying selection criteria for inadequately observed sources and applying weighting procedures for different measurements at the same wavelength these data form a catalogue of 510 sources with a maximum of 120 entries per source. It is available on magtape (or cards...) from the Strasbourg Stellar Data Center. The catalogue is described in detail in a forthcoming publication (Eichendorf and Reinhardt, 1978a); details related to the catalogue as available from Strasbourg are given in Eichendorf and Reinhardt (1978b).