There is now considerable discussion whether intracytoplasmic sperm injection (ICSI) should be used in all cases of IVF. A critical and balanced view of the current literature is presented. The difficult question is how to identify men with apparently normal semen who are likely to fail to achieve a pregnancy using IVF. In conclusion, from both the safety and scientific viewpoint, ICSI should only be used in cases where success at IVF is regarded as unlikely.