Abstract: Keratoconus is pathological condition of eye characterized by paraxial stromal thinning leads to corneal surface distortion. It is well documented that the corneal thickness is abnormally altered in keratoconus; but it seems that racial differences are exist in the amount of changes. This study compared the central and peripheral corneal thicknesses (CCT and PCT, respectively) in eyes with and without keratoconus in a large Iranian population. CCT and PCT were measured by ultrasonographic pachometry in ten thousands eyes undergoing refractive surgery during a six-year period (2003-2010) in Tabriz Nikookari Teaching Eye Hospital. These two variables were compared between the eyes with and without keratoconus. Two hundred and two eyes out of ten thousand eyes were diagnosed with keratoconus. The mean CCT and PCT were significantly lower in the eyes with keratoconus comparing with the others (CCT: 479.90±28.07 μm vs. 534.12±39.35 μm; p<0.001; PCT: 515.04±148.44 μm vs. 560.78±32.93 μm; p<0.001). This study confirmed that both CCT and PCT are lower in the eyes with keratoconus. Likewise, due to large sample size, the results can be used for epidemiological purposes.