The paper describes the process of evolving a controlled Nursing Vocabulary for indexing and information retrieval purposes. The vocabulary is based on terms of the thesaurus of Medline i.e. MeSH (Medical Subject Headings) by National Library of Medicine and the International Classification for Nursing Practice (ICNP) by the International Council of Nurses. The vocabulary consists of 10 themes central to nursing domain. The vocabulary is added as an independent theme to the Finnish thesaurus FinMeSH. The validity of the vocabulary has been tested for indexing nursing research once and has afterwards been revised. The validity will be tested again during spring 2002.