The sylvian triangle is the sigle most important vascular configuration in the angiographic localization ofsupratentorial hemispheric tumors. Vlahovitch et al. recently described a new system for measuring the sylviantriangle on the lateral cerebral angiograms and thereafter Gonzales et al. evaluated the Vlahovitch system, usingcomputer programing, and reported its diagnostic values and advantages. The present study was designed to containnormal measurements of the sylvian triangle in Koreans. The author measured all extremities, angle, height, andsuperior insular line of the sylvian triangle in 100 lateral carotid angiograms of 68 males and 32 females, whichwere considered anatomically normal. The results were as follows; 1. Extremities of the sylvian triangle; Theanterior extremity (a) of the sylvian triangle was close to or on the line MM' in the great majority of the casesand, on the average, lay 1.55mm(SD±1.01mm) behind the line. The posterior extremity (b) lay 15.05mm (SD±6.49mm)behind the line AA' and the inferior point (c) lies at the junction of one-fourth of AA' and one-third of AO witha variation of 3.92mm (SD±1.70mm) in all directions, on the average. 2. Angles of the sylvian triangle; The meananterosuperior angle (i) was 70degrees (2SD±6.67degrees), and the mean posterior angel (ii) was 31degrees(2SD±6.50degrees), and the men inferior angle (iii) was 79degrees (2SD±7.34degrees). 3. The height of thesylvian triangle (cn) was found to be one-fourth the hemispheric height and the mean height was 2.83 mm(SD±0.23mm). 4. Superior border of the sylvian triangle; The superior insular line is located 6.22mm(SD±3.66mm),on the average, below the midpoint of the hemispheric height(x).