In a previous report, we investigated inflammatory responses induced by injecting Listeria monocytogenes into one testis of a mouse. We demonstrated that the contralateral testis also developed an orchitis despite the absence of bacteria, indicating that the inflammation on the uninfected, contralateral side was of autoimmune character. In both infected and autoimmune testes, gammadelta and alphabeta T cells infiltrated during the inflammation. In this paper, we present the data of a comparison of the character of gammadelta T cells of the infected and autoimmune testes. In both testes, gammadelta T cells appeared to be activated, as assessed by high CD44 and low l-selectin expression. Analysis of T-cell receptor (TCR) usage in both inflammation types revealed the same gammadelta TCR repertoire. Finally, the semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated that gammadelta T cells in both types of inflammation were capable of producing interleukin-2 (IL-2), IL-4, interferon-gamma (IFN-gamma), IL-10 and transforming growth factor-beta (TGF-beta). These results imply that gammadelta T cells present in infected-induced and autoimmunity-induced inflammation have the same characteristics and could work as immunoregulatory cells.