In 1997, the Polish Registry of Congenital Malformations (PRCM) was established, to fulfil epidemiological, prophylactic, socioeconomic and scientific functions. The PRCM is a population-based registry monitoring currently about 300 000 births a year in 13 provinces. Such a large area and population require a special organizational structure of the Registry. The PRCM Central Working Group and the computer database are located in the Department of Medical Genetics, University of Medical Sciences, Pozna?. Here the data are collected, validated, encoded according to the ICD-10, and analysed. Provincial Working Groups are responsible for supervision of data collection in the given province. The PRCM staff has grown from about 250 members in 1997 to more than 400 members today. The PRCM collects information on structural defects diagnosed before the end of the second year of life. Minor anomalies are excluded from the registry. The main source of information is a registration form filled up by the physician diagnosing the anomaly. Since 2004 also electronic reporting has been possible. On 28 September 2005 there were 54 020 entries in the database concerning 33 729 children with at least one congenital malformation and 1261 control entries concerning children without malformations. The PRCM is also an important source of identification of families at genetic risk. Education of physicians and the community in the field of genetic counselling is also an important aim of the PRCM. Since 2001, the PRCM has been a member of the Eurocat. Detailed information on PRCM organization, electronic reporting, and results are available at the PRCM website (www.rejestrwad.pl).