Errare humanum est, perseverare diabolicum

Medical error is a subject that receives increasing attention from physicians, legislators and attorneys. Taking the lead from a personal event in the author's career, the article focuses on errors in the practice of anatomic pathology. It discusses the difficulties of objectively separating true diagnostic mistakes from the great variability of informed opinions that exists in pathology; such variability makes the definition of error particularly arduous. Some of the possible causes of diagnostic errors and ways to deal with their potentially disastrous consequences are also discussed.