Abstract Rauscher leukemia virus (RLV)2 has been reported to induce little or no interferon in a number of murine systems, such as BALB/c (1) and NMRL (2) strains. In the case of the random-bred CD-1 strain, Glasgow and Friedman (1) observed relatively high serum levels of interferon in adult RLV-infected mice with accompanying resistance to the disease. We have extended these studies to an investigation of the interferon response to RLV in the autoimmune New Zealand Black (NZB) model and for comparative purposes have included the C57BL/6 and BALB/c strains. The female NZB mice employed represented the seventh and eighth generations in this laboratory from breeding stock (generations 57 and 58) obtained from the Otago University Medical School, Dunedin, New Zealand, and have since been maintained in a closed colony. These NZB mice are vigorous, healthy, and relatively long-lived with 50% survival at 17 months; their microbiologic status has not been assessed.