There is a lack of knowledge regarding graduate nurses' experiences of preparation in nursing education for their work in health care. The aim was to describe registered nurses' (RNs) perceptions of preparation in nursing education for their professional work and development in the nursing profession. The sample consisted of 339 RNs with 3 years experience taken from Swedish class registers for graduation in nursing education. A questionnaire was sent by post to 327 RNs. The response rate was 70.3%. The results (n=219) show that the most important domains of knowledge for RNs' work were biological science, medical science and nursing, whereas humanities and social science were less important. The importance of medical science was significantly lesser in community care and nursing in emergency care. Research methodology was of little importance for RNs' work. RNs could not make use of or conduct research in their work but research planning was significantly higher for those with extensive university education. This study mainly indicates that RNs need a stimulating work environment, including mentoring and support to enable continuous professional development in health care.