A total of 116 female patients with painful bladder syndrome/interstitial cystitis aged 32-78 years (mean age 56 +/- 2.4 years) entered the trial. They were divided into two groups according to treatment. Group 1 (n = 54) received 10-day combined conservative treatment consisting of antimicrobial drugs (if urinary infection was diagnosed), angioprotectors, mast cell activity stabilizers and bladder instillation with combined solution. Group 2 included 62 patients whose treatment included complex anti-inflammatory therapy in combination with HBO sessions (7-10 sessions in barochamber OKA-MT, 2.0 +/- 0.2 atm). Subjective (the disease course, pain intensity, 24-h and nocturnal pollakiuria, effective urine volume) and objective (microcirculation in the bladder wall) results were assessed. Dopplerograms revealed venous stagnation. Patients of group 2 had a persistent improvement of microcirculation in bladder mucosa as shown by better blood flow in the veins and arterioles. In group 1 the above improvement was less pronounced. Thus, HBO in combined treatment of interstitial cystitis improves treatment results and promotes long-term remission of the disease.