Objective : This study is to evaluate the efficacy of intracytoplasmic sperm injection (ICSI) for previous fertilization failure with conventional in vitro fetrtilization (IVF), compared with ICSI for male factor. Method: The author analyzed the 3 years of clinical experience with ICSI retrospectively, between the conventional IVF failure group (IVF failure) and male factor group (male factor). Surgically retrieved epididymal or testicular spermatozoa for ICSI were excluded. The IVF failure group was 13 cycles of 6 patients and male factor group was 30 cycles of 15 patients. Results: The fertilization rates of the IVF failure group and male factor group were 63% and 66% respectively (p=0.635). The clinical pregnancy rates of the both group were 23.1% and 26.7% (p=0.804), and that of live birth rates were 15.4% and 13.3% (p=0.858). There were no significant difference between the two groups. Conclusion: The author concluded that ICSI can overcome previous fertilization failure, with the same fertilization and clinical pregnancy rates seen in patients with male factor.