Introduction. Congenital malformations have been known about for ages, but the reasons for their development have always been shrouded in mystery. All efforts to explain such reasons as to relating to the natural forces of God’s revenge have not stood the test of time. Still, the knowledge concerning the aetiology of malformations is not complete; we know, however, about many factors which may contribute to their development during various stages of embryogenesis. Aim. The aim of this paper is the analysis of specific factors which may have contributed to the development of congenital malformations in children born in the Province of Warmia and Mazury between the years 1999 and 2000. Materials and methods. The author of this paper, who is involved in the creation of the Polish Register of Congenital Malformations (PRCM), evaluated case records of newborns who had been reported to have been born with congenital malformations. The data recorded in this Register, maintained by the Chair and Department of Medical Genetics at the Medical Academy (at present Medical University) in Poznań, was verified by specialists, and later analysed according to the methodological principles of this work. The analysis included: fetal age and birth weight, mother’s age and education, as well as mother’s place of residence. Statistical analysis was carried out by means of Statistica v.6.1 software. Results and discussion. Congenital malformations were found in 276 boys, with a malformations incidence factor of 166.8/10000 for boys, and in 212 girls, the malformations incidence factor being 136.2/10000 for girls. The higher incidence of congenital malformations in boys was caused by a nearly 10 times higher incidence of urinary system defects. The incidence of congenital malformations in newborns whose mothers resided in cities amounted to 132.9/10000 of newborns born in cities. The incidence of congenital malformations in newborns of mothers residing in the country was 141.9/10 000 of newborns born in the country. It was also noted that the incidence of congenital malformations was 2–3 times higher in children with low birth weight in comparison to the general population. The highest incidence of congenital malformations was found in those children whose mothers were 35 years of age or older at the time of giving birth. Advanced maternal age was the most significant factor in the development of malformations caused by chromosome aberrations. Creating a district map presenting the incidence of malformations may be the first step to further research concerning those specific geographical regions at high risk of congenital malformations. The highest incidence, irrespective of the type of malformation, was observed in the districts of: Mrągowo, Ostróda and Braniewo, whereas the lowest was found in the districts of: Ełk, Olecko and Gołdap, and Giżycko. Conclusions. Having analysed all pertinent data, it was then concluded that: 1. Male sex correlates with the incidence of congenital malformations of the genitals. 2. Low birth weight correlates with an increased incidence of congenital malformations. 3. The incidence of congenital malformations in particular districts is diversified, pointing to the significance of necessary further research in order to identify those specific geographical locations having the highest malformations incidence factors.