Objectives: Mycoplasma genitalium infections are suggested as causes of a number of pathological outcomes in pregnant women. The aim of this study was to evaluate the frequency of M. genitalium infections among pregnant women and its association with spontaneous abortion. Methods: In this case–control study we included 109 women with spontaneous abortion with a gestational age of 10–20 weeks (patients), and 109 women with normal pregnancy with a gestational age of 20–37 weeks (controls) in Sanandaj, Iran. Using specific primers and extracted DNA from endocervical swabs, a polymerase chain reaction was conducted for the detection of M. genitalium infection in both groups. Results: The frequency of M. genitalium infection in patient and control groups was one (0.91%) and three (2.75%), respectively. In both control and patient groups using Fisher test, no association between mycoplasma infection and spontaneous abortion was seen. Conclusion M. genitalium may be positive in the genital tract of some pregnant women but was not associated with spontaneous abortion. Further powerful studies with larger sample sizes are needed for the determination of a possible role of M. genitalium in pregnancy outcomes and spontaneous abortion.