The aim of this study was to describe essential competencies relevant for professional renal nursing in Sweden. A Delphi study with four rounds was conducted from November 2008 to April 2009. A national sample of renal nurses was used to achieve consensus about the core competencies required. The 43 competencies were reviewed for face validity by external experts representing general nursing, renal nursing, stakeholders and nephrologists. The core competencies were categorised in nine areas according to their structure; nursing and medical science, information and teaching, examinations and therapies, promoting health and preventing ill health, palliative care, safety and quality, care environment, research and development and management and cooperation in the patient care pathway. Altogether these categories represent a national description of competence in renal nursing.