Members of two Leber families previously published in 1944 (Lundsgård) and 1968 (Seedorff), were traced during the years 1968-1980 and questioned in 1981 about their eyesight. Age at onset, manifestation rate, the frequency of onsets of the disease in the families in the course of time, the procreation in the female lines of descent, and the carrier rate are considered. Women born in the female lines of descent were found to be carriers provided that they had a sufficient number of descendants so that the disease had a possibility of manifesting itself.