Peer evaluation in nursing is a method by which the nurse evaluates the work of a peer, according to set evaluation criteria. The aim of the study was to clarify the potential significance of peer evaluation with regard to nurses' career development and relates to the introduction of a career development programme for nurses in a Finnish University Hospital. The research concepts were created on the basis of literature analysis. The concepts served as a basis for data collection, and five open-ended questions were devised from them. Informants (n = 24) gave free-form essay-type answers to these questions. The material was analysed using qualitative content analysis. The results indicate that self-evaluation constitutes the basis for peer evaluation. Peer evaluation allows nurses to give and receive professional and personal support promoting professional development. Professional support offers possibilities for change and alternative action. Personal support requires respect for the peer's equality and individuality. Personal peer support can decrease feelings of uncertainty and insecurity caused by work. The conclusion is drawn that peer evaluation is a means of promoting nurses' professional development to further on-the-job learning in collaboration with peers.