OBJECTIVE There are numerous published papers on TAR syndrome. Nevertheless, most of them refer to cases or families with several affected members, but we could find no publication epidemiologically analyzing a consecutive series of cases. METHODS We show the characteristics of the six cases with TAR syndrome identified in the consecutive series of 25,967 malformed live born infants detected among 1,431,368 live births surveyed by the ECEMC (Spanish Collaborative Study of Congenital Malformations) since April 1976 until June 1997. RESULTS The minimal estimated frequency of TAR syndrome in our area is 0.42 per 100,000 live born infants, with a confidence interval of 0.15 to 0.91. There was no known consanguinity among the cases' parents, nor other affected family members. The sex ratio was 1:1. Although it is generally considered that the syndrome is autosomal recessive, genetic heterogeneity cannot be ruled out. CONCLUSIONS Our cases concur with published data with respect to the low frequency of consanguineous parents. However we did not find a higher proportion of girls affected as has been described previously.