Pericentric inversions are among the most frequentchromosomal rearrangements with a frequency of 1-2%. Thereis no phenotypic effect in the majority of pericentric inversionheterozygote carriers, when it is a balanced rearrangement.However, miscarriages, infertility and/or chromosomallyunbalanced offspring can be observed in carriers of a pericentricinversion. This is a case of pericentric inversion of one chromosome21: inv (21) (p12; q22) in repeated pregnancy loss. A couple wasreferred for cytogenetic examination due to idiopathic miscarriages.The proband proved to be a carrier of chromosomal inversion andher partner's karyotype was found to be normal. The karyotypeof the proband is 46, xx, inv (21) (p12; q22). This abnormalkaryotype is reported as a probable reason of miscarriage in theinvestigated couple. The risk of further miscarriages and the riskof a progeny with abnormal karyotype are rather high. Therefore,amniocenthesis for finding the chromosomal abnormality as aprenatal diagnosis are proposed for the patient if future pregnancydoes not lead to miscarriage.