【Objective】 To evaluate the effect of teratozoospermia on the outcomes of intracytoplasmic sperm injection (ICSI). 【Methods】 A total of 445 ICSI cycles were reviewed retrospectively for the pregnancy outcome between October 2009 and July 2012 in our IVF center. ICSI cycles were classified into 3 groups based on sperm morphology according to the WHO Laboratory Manual for the Examination and Processing of Human Semen (2010

the 5th edition): Group A (normal sperm≥4%

n = 296); Group B (normal sperm≥1% and <4%

n = 74); Group C

severe teratozoospermia (normal sperm <1%

n = 75). The observational outcomes included oocyte maturation rate

fertilization rate

cleavage rate

implantation rate

clinical pregnancy rate

ectopic pregnancy rate

multiple pregnancy rate and miscarriage rate. 【Results】 The oocyte maturation rate of group A

B

and C were 85.7% (3367/3927)

82.7% (645/762)

and 85.9% (773/900)

the fertilization rates of group A

B

and C were 75.5% (2543/3367)

81.1% (523/645)

and 80.1%(619/773)

respectively

and the corresponding clinical pregnancy rates were 44.9% (133/296)

41.9% (31/74)

and 46.7% (35/75). There was no statistical difference in the oocyte maturation rate

the cleavage rate

the high quality embryo rate

the implantation rate

the clinical pregnancy rate

the ectopic pregnancy rate

and the miscarriage rate among the three groups. However

the high-quality embryo rate (67.6%

405/599)

the implantation rate (32.1%

53/165) and the pregnancy rate (46.7%

35/75) were observed in group C with the most severe teratozoospermia. 【Conclusion】 ICSI is a method of choice in patients with teratozoospermia. The percentage of morphologically normal sperm is not statistically correlated with clinical outcomes. Sperms selected for ICSI allowed excellent outcomes even in the samples with severe teratozoospermia.