This review summarizes the introduction of ICSI in the early 1990s as an assisted fertilization procedure in couples with severe male factor infertility, who could not be helped by conventional IVF. As for current practice, the indications for ICSI using fresh or frozen-thawed ejaculated, epididymal or testicular sperm are reviewed as well as some reports on the use of ICSI in non-male infertility. The main steps in an ICSI cycle are well standardized by now; it is rare that ICSI cannot be carried out and the results in terms of fertilization, embryo transfer and clinical pregnancy rate have been consistent for many years, indicating that a substantial number of couples can now have their own genetic child instead of having to use artificial insemination with donor sperm. This review also emphasizes the importance of assessing the risk of ICSI for the children: there is a slight increase in de novo chromosomal abnormalities, the major congenital malformation rate is similar for IVF and ICSI (between 3 and 4%), and at approximately 2 years of age the developmental outcome as assessed by the Bayley scale is similar for IVF and ICSI. Recent publications mention that a few children are affected by diseases caused by imprinting disorders. Future studies are needed to assess the association between assisted reproductive technologies and imprinting disorders. ICSI is frequently used in couples undergoing preimplantation genetic diagnosis. PGD stricto sensu as well as PGD for aneuploidy screening and for Klinefelter patients are reviewed using the ESHRE PGD Consortium data.