In addition to contact force (CF), catheter stability is considered to be an important factor in creating radiofrequency lesions.To evaluate the catheter stability during pulmonary vein isolation (PVI) using CF-sensing catheter.PVI was performed in 32 patients using a CF-sensing catheter. Operators were blinded to CF. The application was arbitrarily defined as a "visually unstable" point if the catheter moved ≥ 4 mm. Data were analyzed according to 6 predefined segments for the ipsilateral PVs. As a parameter of catheter stability, the standard deviation (SD) of CF and relative standard deviation (RSD = 100 × SD of CF /average CF) were introduced.A total of 932 RF applications with 426 visually unstable points (UP; 45.7%) and 506 stable points (SP; 54.3%) were analyzed. SD was significantly higher at UP (8.0 g versus 5.7 g, P < 0.001), and RSD was significantly higher at UP (43.7% versus 26.5%, P < 0.001). Higher RSD was associated with visual instability in all the segments of both PVs, however, higher SD of CF was not in all segments. At the antero-superior segment of the LPV, and the roof and posteroinferior segments of the RPV, the RSD values were over 50%, suggesting catheter instability.Catheter instability occurred in 45% of ablations during PVI and was predominantly located in the antero-superior segment of the LPV and postero-inferior segment of the RPV, which may result in incomplete lesion formation. RSD had significant correlation with visual catheter stability.