Objectives: The aim of this study is to provide to indexers MeSH terms to be considered as major ones in a list of terms automatically extracted from a document. Material and methods: We propose a method combining symbolic knowledge - the UMLS Metathesaurus and Semantic Network - and statistical knowledge drawn from co-occurrences of terms in the CISMeF database (a French-language quality-controlled health gateway) using data mining measures. The method was tested on CISMeF corpus of 293 resources. Results: There was a proportion of 0.37