EN
In this paper, Author presents basic definitions found in the Polish literature concerning medical error and medical event. Author proposes her own definitions for the terms. The concept of a medical event was first used in the recent Act of 28 April 2011 amending the act on the patient's rights and Patient's Ombudsman, and the act on obligatory insurance, Guarantee Fund and the Polish Motor Insurers' Bureau, while the notion of a medical error has been used for long. Thus, Author examines differences between the two terms. Based on analysis, Author concludes that the occurrence of a medical event does not require us to demonstrate who has contributed its occurrence, while such demonstration is required in the case of a medical error. The two terms are associated with different scopes of liability for the occurred medical event or error, that is, a medical event is limited to therapeutic activities activity of hospitals while liability for a medical error may be attributed to all medicinal entities.