The diverging views expressed in the literature on the inheritance of keratoconus gave us cause to examine the genetic relationships in 304 cases of keratoconus from our own clinic material. In the 22 cases (19 families) where two or more family members were affected, the genetic relationships generally indicated a multifactorial mode of inheritance, although isolated dominant or recessive variants could not be excluded. The assumption of a multifactorial inheritance is further supported by the occurrence of keratoconus in connection with various syndromes, as well as the fact that keratoconus does not only express itself in sharply defined stages, but also occurs in all possible degrees, from almost normal to the extreme.