Objective: To determine the prevalence of Y- chromosome microdeletions in recurrent pregnancy loss (RPL) couples as compared with couples with male factor infertility and fertile couples. Design: Controlled clinical study. Setting: Andrology laboratory and RPL clinic. Patient(s): Seventeen men from RPL couples, 18 men from couples with a live birth and no history of miscarriages, and 10 men from couples with male factor infertility. Intervention(s): Buccal smears for Y- chromosome microdeletion testing. Main Outcome Measure(s): The DNA was tested for microdeletions in the proximal AZFc region by polymerase chain reaction (PCR). Result(s): Fourteen of the 17 men (82% ) tested had microdeletions in one or more of the four segments studied. Two of the 10 male factor infertility patients (20% ) had microdeletions in 2 different segments. None of the 18 fertile men had any microdeletions in the 4 segments of the proximal AZFc region studied. Conclusion(s): The prevalence of the Y- chromosome microdeletions in the proximal AZFc region was much higher in men from RPL couples than from fertile or infertile couples. Although these patients are from a tertiary referral center that may skew the population and findings, one may consider Y- chromosome microdeletion testing particularly of the AZFc region in the evaluation of RPL couples when all other tests fail to reveal the etiology. Objective: To determine the prevalence of Y-chromosome microdeletions in recurrent pregnancy loss (RPL) couples as compared with couples with male factor infertility and fertile couples. Design: Controlled clinical study. Setting: Andrology laboratory and RPL clinic. Patient (s): Seventeen men from RPL couples, 18 men from couples with a live birth and no history of miscarriages, and 10 men from couples with male factor infertility. Intervention (s): Buccal smears for Y-chromosome microdeletion testing. Main Outcome Measure (s) : The DNA was tested for microdeletions in the proximal AZFc region by polymerase chain reaction (PCR). Result (s): Fourteen of the 17 men (82%) tested had microdeletions in one or more of the four segments studied. Two of the None of the 18 fertile men had any microdeletions in the 4 segments of the proximal AZFc region studied. Conclusion (s): The prevalence of the Y-chromosom e microdeletions in the proximal AZFc region was much higher in men from RPL couples than from fertile or infertile couples. one may consider Y-chromosome microdeletion testing particularly of the AZFc region in the evaluation of RPL couples when all other tests fail to reveal the etiology.