Objective: Prenatal diagnosis of foetal trisomies is usually performed by cytogenetic analysis. This requires lengthy laboratory procedures and it is expensive. Here, we report a retrospective study of quantitative fluorescent polymerase chain reaction (QF-PCR) for prenatal detection of trisomies 13, 18 and 21. Methods: QF-PCR was performed on a total of 447 amniotic fluids blindly analysed without any knowledge of the cytogenetic results and 43 samples with known karyotype. All samples were tested with at least 4 small tandem repeat markers specific for each chromosome 13, 18 or 21. Results: QF-PCR results on amniotic fluid were consistent with conventional cytogenetic data. QF-PCR detected 5 cases of trisomy 21, 2 cases of trisomy 18, 1 case of trisomy 13 and 1 case with Klinefelter’s syndrome. Conclusions: QF-PCR has proved to be very useful in clinical settings, since it allows the detection of major numerical disorders in a few hours after sampling and thus reduces parental anxiety.