The Robertsonian translocation 5(13;14)(p11;q11) was studied in three families with probable common ancestry in Eastern Finland. In the largest family the translocation has segregated through at least nine generations. The same family also included a female who was homozygous for t(13;14). No clear-cut effect of the translocation on fertility could be demonstrated and only one case of trisomy 13 was recorded in the offspring of t(13;14) carriers. The results are discussed, with implication for human chromosomal evolution.