To assesses chromosomal aberrations in the abortus in recurrent miscarriage, in the presence of parental chromosomal aberrations.Retrospective comparative cohort study.Tertiary referral unit in university hospital.One thousand one hundred eight patients with 3-16 miscarriages before 20 weeks gestation; 113 patients with and 995 without chromosomal aberrations.Karyotyping by standard G-banding techniques of both parents, and of 205 abortuses collected at curettage.The incidence of the euploidic and aneuploidic abortuses according to the parental karyotype.Two hundred three abortuses were successfully karyotyped. In 164 embryos of patients with no parental chromosomal aberrations, 23.2% (38/164) had chromosome aberrations. Of the 39 abortuses karyotyped in patients with chromosomal aberrations, 17 had normal karyotypes, 8 had balanced translocations, 2 had inversions identical to the parents, and 12 (30.8%) had abnormal karyotypes. This difference is not statistically significant (odd ratio 1.47, 95% confidence interval 0.63-3.39). Only 4 of the 39 karyotyped abortuses had an unbalanced translocation.Parental karyotyping was not particularly predictive of a subsequent miscarriage as a result of chromosomal aberrations as 43.5% of abortuses were euploidic, and the parental aberration was only passed on to the abortus in 10% of cases.