Objective: Analysis of quarterly incidences of selected types of birth defects in the Czech Republic in 1994-2000. Setting: Institute for the Care of Mother and Child, Prague; Department of Medical Genetics, Thomayer Hospital, Prague and Institute of Health Information and Statistics, Prague. Type of study: Retrospective analysis of quarterly data from registers of birth defects in the Czech Republic. Methods: Processing and analysis of incidences of selected birth defects in the Czech Republic in relative numbers (per 10 000 liveborn infants). The ratio of observed/expected valueswas calculated. Results: During the period between Jan. 1 1994 and Dec. 31 2000 a total of 654 695 liveborn infants were born (for 2000 preliminary data). This number included 18 008 infants with one or more birth defects. The mean incidence of all cases during the observation period was 262.99 per 10 000 liveborn infants. In the analysis the authors discuss in detail also the frequency and its changes of eleven selected types of birth defects.Conclusion: Continous registration and analysis of the incidence of inborn defects are essential as the basis for evaluation of the influence of the mentioned factors on the incidence of inborn defects.

        Key words: inborn defect, population teratology, teratogen, incidence, Czech Republic