A familial 4;13 translocation showed three different segregations and two kinds of imbalances: two brothers had a distal trisomy 13 [46,XY,-4,+der 4, t(4;13)(q35;q14)mat] and their maternal uncle had a proximal trisomy 13 [47, XY,+der13,t(4;13)(q35;q14)mat]. A relative excess of abortions was observed in this family, probably related to a lethal variety of segregation.