Since the establishment of intracytoplasmic sperm injection (ICSI) in 1992, sperms have been observed, evaluated, and selected under an inverted microscope at 400 × magnification for ICSI. Intracytoplasmic morphologically selected sperm injection (IMSI) is a technique in which sperms are selected for micro insemination by more precisely observing their morphology, at increased magnification under an inverted microscope used for micro-insemination and enhancing the image resolution. Approximately 20 years have passed since IMSI was developed, and its efficacy has only been confirmed in cases with a high rate of sperm aneuploidy, a high rate of sperm DNA fragmentation, and repeated ICSI failures. It is well-known that the quality of sperms has a profound effect on the quality of embryos which may eventually become children. Therefore, when micro-insemination is performed, sperms should be selected by not only paying attention to their motility, but also by closely observing their morphology. Those engaged in fertility treatment should always keep in mind that sperm selection itself has a significant influence on patients' lives.