Intracytoplasmic sperm injection (ICSI) is performed in cases of infertility by injecting a motile and morphologically normal sperm cell under a routine ×400 magnification at which is hard to distinguish morphologically healthy sperm. Recently, the use of high-powered differential interference contrast optics gave the opportunity to select a sperm under ultra-high magnification of ×10,160. The aim of the present study was to evaluate the efficacy of the intracytoplasmic morphologically selected sperm injection (IMSI) technique in different infertility populations undergoing ICSI. Main outcome measures of routine ICSI were compared with IMSI in three different groups of patients (1, non-selected; 2, male infertility; and 3, repeated implantation failure group). Results were analysed to evaluate the effects of the IMSI procedure and to find the most suitable group of patients who may benefit from the procedure. IMSI caused a significant increase in the fertilization and top quality embryo rates in the male infertility group and a significant increase in fertilization and pregnancy rates in the repeated implantation failure group, whereas no effect was observed in the non-selected group with patients of various indications. A positive effect of IMSI on the outcome of male factor infertility and repeated implantation failure patients was observed. Data observed confirmed that the application of IMSI was beneficial for a selected group of patients with male factor infertility and repeated implantation failure.