OBJECTIVE: To audit the development and success rate of prenatal detection of congenital heart defects (CHDs), and to evaluate the effectiveness of diagnostics performed in standardized scanning planes. SETTING: Department of Pediatrics, University Hospital Ostrava. DESIGN: Retrospective study. METHODS: Ultrasound examination of fetal heart (fetal echocardiography) was performed in the second trimester pregnancy. The observed region was the Moravian-Silesian region; the assessment was performed in the retrospective study performed between 2000- 2016. The knowledge of all significant heart defects in the region, processing of data from genetic reporting, further examination of all prenatal pathologies by a pediatric cardiologist, presence of a pediatric cardiologist at all autopsies, with a precise description of the defect, birth of a pathological new-born at a specialized centre. Analysis of detected CHDs was performed in relation to the ultrasound scans used. RESULTS: During the monitored 17-year period, a total of 748 (3.8 cases per 1,000 foetuses) of prenatally identified and postnatally significant CHDs were observed in the total population of 198,300 foetuses. There were 53% (393/748) CHDs detected prenatally and 47% (355/748) of cases were not prenatally recognized. The effectiveness of CHD screening has improved progressively, from the initial 10% up to the current 74%. The best results were obtained using the basic four-chamber (4CH) scan; the results in practice gradually decreased, from the basic 4CH projection to the aortic arch. CONCLUSION: The effectiveness of prenatal detection of congenital heart defects gradually improves, namely in cases of hypoplasia and significant ventricular anomalies, with up to 100% prenatally detected cases in the past three years. The level of detection statistically decreases, from the four-chamber projection to out-flow tracts, great arteries and the aortic arch. Congenital heart defect is generally well detectable prenatally, and is usually observed as an isolated anomaly. The most important factors include a precise diagnosis, overall examination of the pregnancy and correct counselling provided for the affected family.