A male with gonadal dysgenesis and a 22p+ was observed. Molecular and Clinical Cytogenetic studies have been carried out on the members of the family. The results showed that there was a 22p+ marker chromosome transmitted from the maternal grandmother of the proband to 6 members of this family. Its short arm showed a homogeneously dull stained region in C-banded preparations and a narrow dark or light stained band in R-, G-banded preparations respectively. A large Ag-band or double NORs was also observed on p+. The chromosomal in situ hybridization with tritium labelled rRNA gene probe demonstrated that the distribution of the silver grains was along the entire p+ of the marker chromosome. The number of silver grains on the short arm of the p+ was 3.9 times as that of any other normal acrocentric chromosomes. Two cases of female with repeated spontaneous abortions and 2 cases of male with gonadal dysgenesis were found by family study. Our studies, combining with previous literatures suggested that these abnormalities were probably in association with p+ marker chromosome.