Many individuals die suddenly and unexpectedly outside the hospital or in the emergency department (ED). The aim of this study was to determine the perceptions, needs and mourning reactions of their bereaved relatives and to assess the relationship with the cause of death. Data were collected prospectively in the emergency department of a university hospital by means of an interview and a standardised questionnaire. We registered 339 deaths over a period of 10 months, of which 110 met the inclusion criteria for sudden and unexpected death. The study group included 74 relatives of 53 deceased individuals. The majority of relatives were confronted with a traumatic death outside the hospital. Most frequently reported complaints concerned a lack of information and being left with unanswered questions. Psychological problems related to mourning were mainly associated with a traumatic cause of death. The results of this study highlight the specific needs of relatives in case of a sudden death either outside the hospital or in the ED and may serve as a basis for recommendations for improvement of psychological care of individuals who are suddenly bereaved.