In spite of many researches in this field, more than 50% of transferred embryos don't implant in IVF/ICSI cycles. there are many causes of implantation failure : the most important of them are genetic, anatomic, immunologic,...and there are multiple treatments for them. recurrent implantation failure(RIF) is supposed when there are at least 2 unsuccessful embryo transferred cycles(fresh or freeze) with good quality embryos if female age is less than 40 years. immunological factors don't have fixed definition and treatments. there are some treatment such as prednisolone, IVIG, Intralipid,...and there are not any proved agreement about them. so we designed a double blind randomized clinical trial on 220 infertile women with RIF with immunological factors such as ANA+, ds DNA+, Antithyroid antibodies(Anti TG, Anti TPO)+, CD markers(CD16, CD56 or CD5, CD19)+ and we divided them randomly in two groups. they receive prednisolone 10 mg daily or placebo of prednisolone about 1.5 months before embryo transfer and continue drugs until 12 weeks of pregnancy in women who get pregnant and evaluate pregnancy rate, implantation rate and ongoing pregnancy rate until 12 weeks. treatment with prednisolone seem to improve ICSI outcomes.