Objective: In the preparation of ICSI, cumulus and corona cells should be removed from the oocytes by using a combination of enzymatic (hyaluronidase) and mechanical (pipetting) methods. But little is known about the effects of different degrees of oocyte denudation and incubation time between denudation and sperm injection on the outcomes of ICSI. The aim of this study was to evaluate the effects of varying the degrees of oocyte denudation and the lengths of incubation time from denudation to sperm injection on the outcomes of ICSI. Methods: In experiment 1, patients (oocytes) were grouped into group A and B according to the degree of denudation, complete and partial, respectively. In experiment 2, patients (oocytes) were grouped into group I, II and III according to the length of incubation time of denuded oocytes until sperm injection as < 1, $1{sim}2$ and >2 hours, respectively. Results: There was no significant difference between the degree of oocyte denudation on the survival, fertilization and development rates after ICSI procedure. In case of the incubation time of denuded oocytes until ICSI, survival rates was higher in group III (83.1 %) than in group I (61.5%, p<0.05) or group II (64.3%). However no statistically significant differences were found between incubation time and fertilization or development rates. Conclusions: This study reveals that the outcomes of ICSI are not affected by the degree (complete or partial) of oocyte denudation. However, the denuded oocytes with incubation period of more than 2 hours show better outcomes of ICSI than those with the incubation period of less than 2 hours.