Retinal nerve fiber layer (RNFL) thickness was measured by Nerve fiber Analyzer (NFA II, GDx version 1.0.08, Laser Diagnostic Technologies,San Diego,Ca.,USA) in 270 eyes with glaucoma (151 POAG, 36 pigmentary glaucoma, 83 pseudoexfoliation (PE) glaucoma), 104 ocular hypertensive (OHT) eyes and 81 normal eyes. According to Humphrey visual field analysis glaucomatous eyes were classified into early (146 eyes), moderate (65 eyes) and severe (58 eyes). Except symmetry, all NFA parameters showed significant difference between the groups (p<0.05). The average value of the Number was 17.63(SD=8.52) in the control group,30.04 (SD=19.1) in the OHT group, and 50.04 (SD=24.60) in the glaucoma group. The number was found significantly higher in advanced stages of glaucoma and the PE glaucoma group.Other GDx parameters were high in the control group and low in the glaucoma group. The RNFL thickness of OHT eyes were in between the control group and early glaucomatous eyes. However,consider- able overlap in measurements between the groups was found. When all 14 parameters were employed, GDx Glaucoma System had sensitivity of 87%,and specifity of 72.8%. Applying lineer discriminant analysis,the group with the highest sensitivity and specifity (85.9% and 74.1%,respectively)was determined as inferior ratio,superior/nasal ratio,superior maximum and the Number. Although NFA is useful in glaucoma diagnosis, it should be used in combination with the visual field analysis and should be considered in follow-up of the patients with glaucoma.