Keratoconus is a bilateral, progressive corneal disease affecting all ethnic groups around the world. It is one of the major ocular problems with significant social impacts as the disease affects young generation, and is the leading cause of corneal transplantation. Although keratoconus is associated with genetic and environmental factors, its precise etiology is not yet established. Results from complex segregation analysis and patterns of gene expression show that genetic abnormalities may play an essential role in the susceptibility to keratoconus. There is a strong association between the polymorphism of a number of genes and corneal curvature. These polymorphisms explain only a small percentage of keratoconus cases, so genetic influences on keratoconus are most likely complex and varied. The aim of this review is to briefly provide the current knowledge on the genetic keratoconus basis - to understand the disease pathogenesis.