According to epidemiological studies adverse drug events are one of the most frequently encountered complications during medical treatment, a leading cause of hospitalisation and frequent cause of death. However, medical malpractice claims due to medication errors seem to be relatively rare. Based on a retrospective multicentre study on medical malpractice cases with lethal outcome (n = 4450), drug related cases (n = 575) were further evaluated. In 50% of cases a causal connection between drug therapy and death could be ruled out already after autopsy. In 232 cases a causal connection between drug therapy and death could be approved (drug allergies, relative overdose, wrong application, mix-up of drugs and sepsis after injection abscess). However, within the legal context only in 70 cases a medication error was approved which was in 42 cases causal for death, in 28 not. Administration of contraindicated drugs, incorrect application and relative overdose in renal insufficiency are the prevalent mistakes. Concerning the frequency of ADE in epidemiological studies medication errors are underreported in all data sources on medical malpractice; this seems to be due to the fact that even doctors and attending physicians rarely recognize an ADE; furthermore approving the connection between drug effect and death is extremely difficult for the expert witness.