Background: Despite the high success rate of ICSI, total fertilization failure still occurs
in 1-3% of all ICSI cycles and can recur in subsequent cycles, even when a sufficient number
of oocytes and motile spermatozoa are available. Several reports show that the majority of
couples suffering from ICSI failure benefit from the application of ICSI combined with
assisted oocyte activation. A variety of artificial activating methods is used in human
assisted reproduction treatment, including physical, mechanical or chemical stimuli, which
provoke one or more calcium rises in the oocyte cytoplasm. Study Design: Randomized
controlled trial. Setting: A university fertility center. Methods: 150 infertile patients who
underwent ICSI and all had history of recurrent fertilization failure. The patients were
randomly allocated into 2 equal groups. Group1=75 patients who underwent ICSI without oocyte
activation. Group2 patients =75 and underwent ICSI Patient underwent ICSI with oocyte
activation. Reproductive outcomes were compared between both groups. Results: there were
significant differences between groups regarding number of oocytes retrieved, number of
mature oocyte, fertilization rate and pregnancy rate. Conclusion: Assisted oocyte activation
with calcium ionophore results in significant improvement in the fertilization, cleavage and
pregnancy rates after ICSI.