Pristane was injected intraperitoneally into mice of several strains, inducing an inflammatory seropositive arthritis in susceptible strains. The evolving histologic features included synovial hyperplasia, periostitis, and progressive marginal erosions. Multiple serologic immune abnormalities, including rheumatoid factor and anticollagen antibodies, also developed. Genetic analysis indicated that the major histocompatibility complex (H-2), C5 hemolytic complement (Hc), Newcastle disease virus-induced interferon (IF-1), and athymic (nu/nu) loci were involved in regulating susceptibility to pristane-induce arthritis. This experimental murine disease may provide a novel model of rheumatoid arthritis.