Abortion is a term used for missing of fetus before 20^th week of pregnancy, which is a common complication of pregnancy and its aetiology usually remains unknown. Known aetiologies for this phenomenon include structural malformation of uterus, genetic anomalies, autoimmune conditions, endocrine defects, coagulative and trombophilic disorders, polycystic ovary, obesity, and lifestyle. Abortion has many mental and physical consequences for the involved couple, especially when it becomes recurrent. Analysis of molecular changes of microRNAs expression that are changed in abortion can help identifying people who are susceptible to abortion and even prevent it. MicroRNAs are a group of non-coding RNAs that regulate a large number of genes. This regulation can occur at transcription level or after transcription. Expression of microRNAs is associated with a variety of diseases. Studies have shown that during abortion, expression of some of these microRNAs is altered (both decrease and increase), which has a large effect on expression of their target genes. Single nucleotide polymorphism (SNP) in coding genes of microRNAs could affect microRNAs’ expression. In the present article, the role and effects of MIRs on recurrent abortion is reviewed.