Introduction: Atrial flutter is a rhythm disturbance caused by a re-entry circuit, located mostly at the level of the right atrium, the left atrium being passively activated. Before radiofrequency ablation, a careful intracardiac mapping and entrainment mapping are mandatory for determining the nature of the reentry circuit and certifying its cavo-tricuspid isthmus dependency. The aim of the study was to evaluate differences in the surface ECG aspect depending on the type of atrial flutter: clockwise or counterclockwise Methods: The study included patients who underwent a radiofrequency ablation procedure for a typical atrial flutter between 2010 and 2013 in Electrophysiology Department of The Rehabilitation Hospital, Cluj-Napoca, Romania. The flutter rotation sequence (clockwise or counterclockwise) was assessed by analyzing the depolarization sequence of the right atrium. The aspect of the F waves in leads DII, DIII, aVF, aVL, V1 and V6 on the surface ECG was then analyzed. We determined sensibility (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) for each aspect. Results: Among the 387 patients, 152 (39.27%) had clockwise atrial fl utter: 112 had positive F waves in inferior leads and negative in V1 (73.68%), Se = 0.89; CI 95% (0.75 – 0.97), Sp = 0.98; CI 95% (0.93 – 1.00), PPV = 0.94; CI 95% (0.81 – 0.99), NPV = 0.97; CI 95% (0.91 – 0.99). There were 235 cases of counterclockwise atrial flutter: 196 had negative F waves in inferior leads and positive in V1 (83.40%). Se = 0.80; CI 95% (0.63 – 0.91) Sp = 0.98; CI 95% (0.95 – 0.99), PPV = 0.87; CI 95% (0.71 – 0.96), NPV = 0.96; CI 95% (0.93 – 0.99) Conclusions: The surface ECG is an important diagnostic tool in the diagnosis of atrial flutter, having an important role in determining the rotation sequence of the macroreentry circuit in the case of a typical atrial flutter, The most useful leads for determining the macroreentry rotation sequence are DII, DIII, aVF, V1, V6 ± aVL.