The Interim Supplement to the General Catalogue of Stellar Radial Velocities (Evans 1979, ISGCRV) contains radial velocities for stars with right ascensions from O through 20 hours. The ISGCRV is intended as a continuation of the General Catalogue of Stellar Radial Velocities (Wilson 1953, GCRV). The ISGCRV resulted from a literature search and data reduction by D. S. Evans covering approximately the years 1951-1977. It contains adopted velocities on the Mount Wilson system. Unfortunately, the individual mea- surements and the literature references could not be included in this version. Both for this reason, and because the ISGCRV covers only O through 20 hours of right ascension (equinox 1900), the ISGCRV should be used with the Bibliography of Stellar Radial Velocities (Abt and Biggs 1972), or the Bibliographical Star Index Retrieval System (Hill et al. 1984).