Searching Ovid: Medline

Boolean Operators

Combine your search terms using the Boolean operators AND or OR to make a final set of results on your topic.

1. First, combine subject headings, synonyms, alternative spellings, etc. relating to the same concept with OR to find references where any of these related terms are present.

   OR

   
   Select the search lines to combine by ticking the relevant boxes and then click the OR button:
   
2. Your combined search will then appear as a new line in your search history:
   
3. Once you have combined the various related terms for each concept with OR, combine the different concepts of your search with AND to find references where both / all concepts are present.

   AND

   
   Select the search lines to combine by ticking the boxes, then click on the AND button:
   
4. Your combined search will appear as a new line in your search history:
   

For more information on how to use Boolean operators, see our Search Tips Guide.