OBJECTIVE To investigate the features of chronic prostatitis with non-neurogenic detrusor sphincter dyssynergia (NNDSD) and the effects of pelvic floor biofeedback in the treatment of the disease. METHODS We included in this study 113 male patients, aged 15 - 48 (mean 36) years and diagnosed as having chronic prostatitis for 1 -2 (mean 1.2) years based on such typical symptoms as frequent micturition, urgent micturition, voiding pain, difficult void, etc, that lasted over 3 months, and the score > or = 1 on the first and second parts of NIH-CPSI. Urethritis, interstitial cystitis, urethral stricture and neurogenic bladder were excluded. All the patients underwent urodynamic examinations for the uroflow curve, Q(max), Pdet. max and MUCP. Biofeedback was carried out for those with non-neurogenic detrusor sphincter dyssynergia, and the effects were evaluated at 10 weeks. RESULTS Twenty-one (18.6%) of the 113 cases were found to be NNDSD. Biofeedback treatment achieved obvious decreases in Q(max) (8.2 +/- 4.1), Pdet. max (125.1 +/- 75.3), MUP (124.3 +/- 23.3) and MUCP (101.5 +/- 43.6), as compared with 15.1 +/- 7.3, 86.3 +/- 54.2, 65.4 +/- 23.0 and 43.5 +/- 16.7 before the treatment (P < 0.05). Statistically significant differences were observed between pre- and post-treatment scores on voiding pain (4.0 +/- 2.0 vs 2.2 +/- 1.7), urination (7.9 +/- 2.1 vs 2.2 +/- 1.9), life impact (9.6 +/- 2.7 vs 2.9 +/- 2.6) and total scores (21.7 +/- 4.8 vs 8.4 +/- 4.6) (P < 0.05). CONCLUSIONS Chronic prostatitis patients with LUTS may have NNDSD, which is urodynamically characterized by low Q(max), high intra-bladder pressure and increased urethral pressure in some patients. Urodynamic examinations may contribute to definite diagnosis and appropriate choice of treatment. Pelvic floor biofeedback has satisfactory short-term effects in the treatment of these patients.