Objective: To determine the frequencies and the characteristics of Y chromosome microdeletion in infertile males from northeastern china in order to perform appropriate therapeutic choices.Methods: A total of 1738 infertile males were involved.Sperm concentration was measured according to standard methods, and karyotype analysis was performed on peripheral blood lymphocytes with standard G-banding.Multiplex polymerase chain reaction (PCR) amplification using nine specific sequencetagged sites (STS) were selected to detect Y chromosome microdeletions.Results: The data showed that the frequency of Y chromosome microdeletion was 8.52%.The commonest microdeletion was detected in the AZFc region, followed by AZFb+c, AZFb, AZFa+b+c, AZFa and AZFa+c.107 cases with Y chromosome microdeletion suffered from azoospermia, 39 from severe oligozoospermia and 3 from moderate oligozoospermia.Karyotype analysis was available for 130 cases with Y chromosome microdeletion and abnormal karyotypes were found in 19 cases (14.6%).The most frequent abnormal karyotype was 46,X,Yqh-.Conclusion: In northeastem china, Y chromosome microdeletion diagnosis should be performed before employment of intracytoplasmic sperm injection, especially in infertile males with azoospermia or karyotype of 46,X,Yqh-.