Cytogenetic study in couples with recurrent reproductive failure allows the detection of structural chromosome anomalies which don't have a phenotypic effect in carriers, but permit the explanation of the production of genetically unbalanced gametes. We present the investigation performed in 270 couples which demonstrated a chromosomal alteration in 9.2% of them. This allows genetic counselling in respect of the importance of the finding, recurrence risk and reproductive alternatives. In 8.6% we found some cellular lines with aneuploidies in sexual chromosomes, which don't represent a such concrete risk.