The aim of this study is to retrospectively analyze 102 cycles which received intracytoplasmic single sperm injection (ICSI) in our lab from January 1998 to December 2000. With the improvements of the technique and environment of the microscopic manipulation from February 2000, the survival rate (90.6%). fertilization rate (73.3%) and embryo development rate (97.3%) of the later stage were significantly higher than those of the previous (68.8%, 39.0%, 78.7% respectively). The clinical pregnancy rate reached a higher level (41.3% and 21.4% respectively). The ICSI technique established currently in our lab can effectively treat the severe male infertility and fertilization failure.