The clinical and cytologic examinations in 6 deaf patients from 2 genealogical trees with chromosomal 15 satellite enlargement, karyotype 46, XY(X), PS++(15) are reported. A proband as well as his brother and sister suffered from phenotype with gradual hearing loss at the age of 12 to 13 and big satellite 15 existed in chromatinic karyotype. His father's phenotype was normal, but karyotype was the same as the 3 siblings of the proband, which suggested that the abnormal chromosome may originate from the father. The proband as well as his mother and uncle from family tree 2 may all suffer from dysaudia in both ears without any cause and with rapid exacerbation of the disease and deafness at last, 1 to 2 years after birth. Based on the fact that they had similar clinical phenotype and karyotype, their delayed deaf-mutism may be related to the structural abnormality of chromosome 15. An examination of the proband's grandparents showed that both phenotype and karyotype were normal. The abnormal chromosome from the proband's mother and uncle may originate from a new mutation. Obviously, the proband's abnormal chromosome originates from the mother. It is estimated that such chromosomal structural abnormality may be caused by some hearing genetic effects.