This paper analyzes the birth and death certificate data of infants who died from the Sudden Infant Death Syndrome (SIDS) before their first birthday. It investigates possible causes of differences in regional mortality and of the significant increase in the number of cases between 1980 and 1987. Moreover, the authors try to assess whether the number of SIDS cases registered by the Austrian Central Statistical Office is plausible. Between 1980 and 1987 the number of SIDS cases increased from 38 (= 2.9% of all infant mortality cases) to 141 (= 16.6%). Moreover, there are significant regional differences in SIDS mortality, varying between 0.3 per thousand in Upper Austria and 2.2 per thousand in Salzburg. Possible causes for these mortality differences are discussed (misclassifications, regional differences in the level of infant mortality). Finally, the authors look at the reliability of the official Austrian SIDS statistics and conclude that the officially announced number of SIDS cases may not give an accurate picture of the situation but is still the best estimate available.