Objective: There is increasing evidence that chronic non-bacterial prostatitis is recognized to be a local inflammatory disease, and there is substantiating evidence to support the role of the inflammatory responses in its pathogenesis, and clinical value in the evaluation of therapeutic efficacy. Prunella vulgaris has been traditionally used in treatment of inflammatory diseases, including of scrofula, goiter, and allergy diseases. In this study, we investigated the effects of Prunella vulgaris on inflammatory cytokines and cytopathological alternation in the rat model of non-bacterial prostatitis induced by castration and $17{eta}-estradiol$ treatment. Methods: Two-month-old rats were treated with $17{eta}-estradiol$ after castration for induction of experimental non-bacterial prostatitis, which is similar to human chronic prostatitis in histopathological profiles. Prunella vulgaris as an experimental specimen, and testosterone as a positive control, were administered orally. The prostates were evaluated by histopathological parameters including the epithelial score and epithelial-stromal ratio for glandular damage, and the expression of inflammatory cytokine genes including the interleukin $(IL)-1{eta}$, IL-5, IL-12, and tumor necrosis factor $(TNF)-{alpha}$. Results: While prostates of control rats revealed severe acinar gland atrophy and stromal proliferation, the rats treated with Prunella vulgaris showed a diminished range of tissue damage. Epithelial score was improved in Prunella vulgaris over that of the control (P<0.05). The epithelial-stromal ratio was lower with Prunella vulgaris when compared to that of the control (P<0.05). In the reverse transcription-polymerase chain reaction (RT-PCR) of inflammatory cytokine genes, Prunella vulgaris inhibited the expression of $IL-1{eta}$ and $TNF-{alpha}$ genes, while it modulated the expression of IL-5, which is an anti-inflammatory cytokine. Conclusions: These findings suggest that Prunella vulgaris may protect the glandular epithelial cells and also inhibit stromal proliferation in association with the immune modulation including the suppression of inflammatory cytokines and promotion of anti-inflammatory cytokine. From theses results, we suggest that Prunella vulgaris could be a useful remedy agent for treating chronic non-bacterial prostatitis.