Summary Examination of fetal tissue from spontaneous miscarriages shows that 50-70% of them were caused by abnormalkaryotype. The most frequent genetic abnormalities include abnormal number of chromosomes, aberration of chromosomes structure and chromosome mosaic anomalies. Objective: the aim of the study was to find out whether there is any difference in the frequency of chromosomal aberrations in patients who miscarried for the first time comparing to patients with recurrent miscarriages. Material and methods: Examination was performed on 129 miscarriage material samples from 128 women. Fluorescent hybridization in-situ (FISH) was used for genetic examination. Results: We received 120 results in which 45 (37,5%) were abnormal. The most frequent chromosomal aberration was trisomy, followed by triploidy and monosomy of chromosome X. Among 59 samples from first miscarriage we found 25 abnormal karyotypes. In the 61 samples from the second, third and the next miscarriages we found 20 chromosomal abnormalities. Conclusions: Frequency of chromosomal aberrations in the tissue from the first miscarriage is significantly higher than in samples from second or following miscarriages, which means that genetic factors are less likely to induce recurrent miscarriages. Genetic results confirm that most chromosomal abnormalities arise de-novo.