A reciprocal chromosome translocation between 7q and 10q and an unrelated Robertsonian translocation involving 14q and 21q were found in a healthy 44-year-old man, in his normal 18-year-old son, and in his mother. They were ascertained through the man's brother, whose grandson has Down's syndrome as a result of an inherited 14q21q translocation. To our knowledge, this is the second report of a karyotype with both reciprocal and Robertsonian translocations in a single subject, and only the fourth report of independently segregating double translocations occurring in more than one generation.