The purpose of this study was to assess the diagnostic value and potentially protective capacity of heat-shock protein 70 (HSP70) in chronic bacterial prostatitis and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). In this study, seminal plasma levels of cytokines (tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β)) and HSP70 were evaluated by enzyme-linked immunosorbent assay in 80 men: 15 healthy controls, 16 men with chronic bacterial prostatitis, 23 men with CP/CPPS IIIA and 26 with CP/CPPS IIIB. The HSP70 levels in chronic bacterial prostatitis and CP/CPPS patients were correlated with chronic prostatitis symptom index (CPSI). Significantly increased levels of cytokines (TNF-α and IL-1β) and HSP70 were observed in seminal plasmas from patients with chronic bacterial prostatitis compared with CP/CPPS patients and controls. However, only IL-1β was significantly elevated compared with CP/CPPS IIIB and controls in patients with CP/CPPS IIIA. HSP70 levels in CP/CPPS patients were significantly lower than that in controls. HSP70 concentration in seminal plasma was negatively correlated with CPSI in chronic bacterial prostatitis. The results indicated that HSP70 and IL-1β appear to be the most reliable and predictive surrogate markers to diagnose chronic bacterial prostatitis and CP/CPPS, respectively. HSP70 has an important protective role in the regulation of cell functions in chronic bacterial prostatitis. CP/CPPS would probably be detrimental to the ability of T cells and consequently suppress the expression of HSP70.