Background　Mapping　using　a　multipolar　catheter　with　small　and　closely　spaced　electrodes　has　been　shown　to　improve　the　validity　of　electrograms　to　identify　endocardial　critical　sites　of　reentry　isthmus　and　foci　of　earliest　activation.　However,　the　feasibility,　safety,　and　clinical　outcome　of　using　such　technology　to　guide　epicardial　ventricular　tachycardia　(VT)　ablation　has　not　been　reported.　Methods　and　Results　Thirty-three　consecutive　patients　from　5　high-volume　centers　were　studied.　These　patients　had　43　epicardial　maps　using　a　novel　64-pole　mini-basket　catheter　to　guide　VT　ablation.　Activation　maps　with　17 832　points　per　map　(interquartile　range:　7621-32 497　points　per　map)　were　acquired　in　11　patients　with　tolerated　VT　(7　focal,　4　reentry).　Substrate　maps　with　40149　points　per　map　(interquartile　range:　20926-49391　points　per　map)　were　acquired　in　30　patients.　Local　abnormal　ventricular　activities　were　consistently　demonstrated　at　the　substrate　regions　of　interest.　Epicardial　ablation　was　performed　in　31　of　33　patients,　with　acute　VT　termination　in　10　of　11　patients　(91%).　Complete　elimination　of　local　abnormal　ventricular　activities　was　achieved　in　25　of　31　patients.　At　a　median　follow-up　of　10　months　(interquartile　range:　4-14　months),　64%　(7/11)　of　patients　who　had　acute　termination　of　VT　and　55%　(11/20)　of　those　who　had　substrate　modification　alone　were　free　of　VT.　There　was　no　immediate　complication　following　epicardial　procedure.　Conclusions　Epicardial　VT　ablation　guided　by　a　mini-basket　catheter　is　feasible　and　safe.　Complete　reentry　VT　circuits　and　foci　of　earliest　activation　were　identified　in　all　inducible　stable　VT.　The　longer　term　clinical　outcome　of　ablation　guided　by　this　novel　mapping　technology　utilizing　small　and　closely　spaced　electrodes　will　have　to　be　determined　with　a　larger　study.