The still living members of the original bleeder family on the Aland Islands described by von Willebrand in 1926 have been reinvestigated by using modern laboratory techniques for the measurement of the Factor VIII complex and with regard to platelet aggregation. The low level of F VIII : C activity demonstrated in 1957 could be confirmed in some of the family members, who however all had only mild bleeding symptoms. More consistently, in 6 out of 10, a low F VIIIR : Ag was found; all of those also had a low F VIII : RCoF. In none of the members were excessively low values for any of the parameters found. However, the spectrum of the whole F VIII complex indicates that the original family described by von Willebrand belongs to von Willebrand's disease, type I.