A systematic review of the second half of the last century suggested that diagnostic errors have decreased over time. Our previous study covering the years 1972-1992 was then the only time series showing a significant reduction of diagnostic errors from a single institution. We report here the results of a follow-up study a decade later. We analyzed discrepancies between clinical and autoptic diagnoses in 100 randomly selected medical patients who died in the wards and in the medical intensive care unit at a tertiary-care teaching hospital in Switzerland in the year 2002. Autopsy rate declined from around 90% in the years from 1972 to 1992 to 54% in the present study. Major diagnostic errors (class I and II) declined significantly from 30 to 7% (P<0.001) over the last 30 years. Class I errors decreased from 16 to 2% (P<0.001) in the year 2002. Sensitivity for cardiovascular diseases increased from 69 to 92% (P=0.006), for infectious diseases from 25 to 90% (P=0.013) and for neoplastic diseases from 89 to 100% (P=0.053). Specificity for cardiovascular diseases increased from 85 to 98% (P<0.001) but was unchanged at a high level for infectious diseases and neoplastic diseases. The number of diagnostic procedures increased from 144 to 281 (P<0.001) with an increase in the number of computer tomography investigations and of tissue sampling in the last decade. The frequency of major diagnostic errors has been further reduced at the beginning of the new millennium probably due in large part to new diagnostic tools.Modern Pathology advance online publication, 24 February 2012; doi:10.1038/modpathol.2011.199.