The symbiotic interaction between pea roots ('Pisum sativum' L.) and the endomycorrhizal fungus 'Glomus mosseae' should lead to specific gene expression of both symbionts. In order to detect symbiosis-related proteins (endomycorrhizins), we used two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) after phenolic extraction of total soluble proteins. Furthermore, to better characterize the molecular changes after fungal infection, two pea genotypes available in our laboratory were used: cv. Frisson (myc⁺) and an isogenic mycorrhiza-resistant mutant (myc⁻). The latter prevents intraradical fungal development. Several differences were observed in polypeptide patterns of silver-stained 2D gels between control and 'G. mosseae'-inoculated roots, after only 7 days of contact between both partners. Some polypeptides already present in control root extracts were altered with fungal colonization, being increased or decreased in intensity. Interestingly, new polypeptides were produced in 'G. mosseae'-infected roots from cv. Frisson whilst in the inoculated mycorrhiza-resistant mutant, different patterns were mainly characterized by disappearance of polypeptides compared to control roots.