To determine the predictive value of an embryonic heart rate (EHR) for a live birth in women with and without a history of recurrent pregnancy loss (RPL). Prospective cohort study with concurrent controls. A subspecialty clinic for couples with RPL. Three hundred pregnant women who previously had been diagnosed with RPL, followed prospectively compared with 300 age-, race-, and gestational agematched pregnant control women. Transvaginal sonography between 6 to 8 weeks of gestation. The EHR was determined between 6 and 8 weeks of gestation by transvaginal sonography. Obstetrical history and current pregnancy outcome were evaluated. Data were analyzed by using the twotailed t test and Fishers exact test. In women with RPL, an EHR predicted a successful live birth in 246 (82%) of 300, compared with 294 (98%) of 300 in control women. The mean (±.SD) EHR from successful pregnancies in the control group (143.2 ±20.8 beats per minute) was significantly higher than the mean in women with a history of RPL (131.4 ±22.9 beats per minute). An EHR in women with RPL is associated with a live birth rate of 82%and is significantly lower than EHR in controls. Clinicians should use this information to counsel patients with RPL. To determine the predictive value of an embryonic heart rate (EHR) for a live birth in women with and without a history of recurrent pregnancy loss (RPL). Prospective cohort study with concurrent controls. A subspecialty clinic for couples with RPL. women who previously had been diagnosed with RPL, followed prospectively compared with 300 age-, race-, and gestational age-matched pregnant control women. Transvaginal sonography between 6 to 8 weeks of gestation. The EHR was found between 6 and 8 weeks of gestation Obstetrical history and current pregnancy outcome were evaluated. The data were analyzed by using the twotailed t test and Fisher  s exact test. In women with RPL, an EHR predicted a successful live birth in 246 (82%) of 300 mean compared with 294 (98%) of 300 in control women. The mean (±. SD) EHR from successful pregnancies in the control group (143.2 ± 20.8 beats per minute) was significantly higher than the mean in women with a history of RPL (131.4 ± 22.9 beats per minute). An EHR in women with RPL is associated with a live birth rate of 82% and is significantly lower than EHR in controls. Clinicians should use this information to counsel patients with RPL.