This report describes six successful pregnancies (five healthy children from four deliveries and two miscarriages) with SrC1(2) oocyte activation using spermatozoa from nine patients with repeated fertilization failure. Oocytes were artificially activated by SrC1(2) 30 min after intracytoplasmic sperm injection (ICSI). Oocytes were placed in 10 mmol/l of SrC1(2) medium for 1 h, rinsed several times, and then cultured in Universal IVF medium. Developmental characteristics of five resulting children until 1 year old were assessed according to the maternal and children health hand book issued by Mothers' and Children's Health Organization in Japan. Mean fertilization rate, mean frequency of good cleaved embryos, pregnancy rate, and implantation rate after artificial activation in nine couples were increased from 21.7 to 64.5% (P < 0.001), from 0 to 15.4%, from 0 to 40.0% and from 0 to 25.0% respectively. Five healthy children were born following ICSI and artificial activation between February 2005 and March 2006. Physical and mental development of the children from birth to 12 months was normal. These suggest the utility and safety of SrCl(2) for patients with repeated failed fertilizations following ICSI and artificial activation.