This review refers to the evolution of ooplasmic injections of round spermatid nuclei (ROSNI) or intact round spermatids (ROSI). Conclusions from their preliminary application in the hamster, rabbit, mouse and human are discussed. Criteria for identification of round spermatids and guidelines/quality control for application of ROSNI/ROSI techniques are emphasized. Although all the animal offspring and the human newborns delivered after ROSNI/ROSI are healthy, additional research efforts are necessary to confirm the safety of these procedures and improve their outcome.