Objective By Comparing the early and late coronary angiograms results between cutting balloon angioplasty (CBA) and plain old balloon angioplasty (POBA), to evaluate the efficacy of CBA on coronary in stent restenosis Methods 166 patients with in stent restenosis after PTCA were randomized into two groups: CBA group (98 cases) and POBA group (68 cases) according to the balloon used Its instant and late mimimal lumen diameters (MLD) diameter stenoses (DS) and restenosis rates after PTCA in above two groups were compared Results Although no significant difference in mimimal lumen diameters (MLD) ([2 6?0 6]mm vs [2 7?0 4]mm), diameter stenosis (DS) (% vs %) was observed instantly after the procedure between the two groups, the required balloon inflation pressure was significantly lower with CBA ([8 3?0 9]atm vs [14 7?4 6]atm, P