Information concerning the prognosis of subsequent pregnancies in patients with reciprocal translocations is limited. This study was performed to determine the percentage success rate with first pregnancies after ascertainment of a carrier status. A total of 2,382 couples with a history of two or more consecutive miscarriages were studied in multicenters. The prevalence of an abnormal chromosome in either partner was examined, and subsequent success rates were compared between cases with and without an abnormal karyotype in either partner. A total of 129 couples (5.4%) had an abnormal karyotype in one partner excluding inversion 9 in 44 men and in 85 women. Thus, 2,253 couples had a normal karyotype in both partner. Eighty-five (3.6%) had translocations, 13 being Robertsonian translocations. Twenty-nine of the 46 cases (63.0%) who became pregnant with reciprocal translocations in either partner experienced a live birth with natural conception. In contrast, 950 of 1,207 cases (78.7%) with normal chromosomes had successful live births, the difference being significant (P = 0.019). No infant with an unbalanced translocation was found in 29 cases of successful pregnancy following recurrent miscarriage. Pregnancy prognosis was worsened with either maternal or paternal reciprocal translocations. Explanation of the success rate with natural conception should be provided before the subsequent pregnancy after ascertainment of carrier status.