Introduction: Pulmonary veins isolation (PVI) is useful method in patients (pts) with mitral valve disease (MVD) and chronic atrial fibrillation (AF) during prosthetic valve implantation.The aim of the study: To evaluate e.ectiveness of PVI in the treatment of AF in pt with MVD during valve implantation.Material and methods: 45 pts (mean age 55 yrs) with AF were operated on for MVD.RF ablation around the pulmonary veins, a lesion between them and to the mitral annulus were performed. There were 44 prostheses implanted, 1 case of mitral valve annuloplasty, associated with tricuspid valve repair (5 pts), aorto-coronary bypass procedure (2 pts), ASD II closure (1 pt).Results: SR was achieved in 2 (44,5%) pts, 21 (46,5%)pts were in AF, 4 (9%) pts needed pacing. No correlation between SR restoration and preoperative echocardiographic parameters, age, gender, NYHA functional class were found. In long-term follow-up 1 pt have reversed AF to SR spontaneously. There were 6 cases of paroxysmal AF,1 pt needed pacemaker implantation. 20 (44,5%) pts are in SR, 20 (44,5%) in AF, 5 (11%) in permanent pacing.Conclusion: PVI with RF use is effective in restoring sinus rhythm in patients with chronic AF secondary to mitral valve disease.