OBJECTIVE To compare the efficacy of four electrocardiographic criteria: Sokolov, Gubner, Cornell and Romhilt indexes, in the diagnosis of left ventricular hypertrophy (LVH) in hypertensive patients. METHODS LVH was analyzed in the electrocardiogram of 30 ambulatory patients presenting with systemic arterial hypertension, classified as mild, moderate and severe, according to the following indexes: Sokolov > or = 35 mm, Gubner > or = 22 mm, Romhilt > or = 5 points and Cornell > or = 20 mm for women and 28 mm for men. Sensitivity, specificity, diagnostic accuracy and other diagnostic variables were determined Mass index of the left ventricle, > or = 98 g/m2 for women and > or = 120 g/m2 for men, obtained by echocardiography, was considered the gold standard for the diagnosis of LVH. RESULTS When electrocardiographic criteria were considered separately, the Sokolov index showed the highest accuracy, with a sensitivity of 40%, diagnostic accuracy of 50% and specificity of 100%; the second most accurate index was Gubner, and Romhilt and Cornell indexes followed. When at least one of the indexes was positive, the sensitivity was 52% and diagnostic accuracy was 57%. CONCLUSIONS The four electrocardiographic indexes were not diagnostic of LVH, when analyzed either separately or together. Considering the high prevalence of this pathological condition, we conclude that a more accurate diagnostic method should be used in this diagnosis.