Proteomics has soon emerged as a powerful tool to point out protein modifications in roots interacting with arbuscular mycorrhiza (AM) fungi. Depending on the developmental mycorrhizal stage and on the available amount of mycorrhizal material, untargeted and/or sub-cellular proteomic approaches were applied to reveal and identify proteins whose accumulation was modified during the AM colonisation of Medicago truncatula roots. For the early stage of symbiosis, the protein patterns obtained from noninoculated roots and roots synchronized for appressorium formation in wild-type (Jemalong J5), penetration-defective (TRV25, dmi3) and autoregulation-defective (TR122, sunn) genotypes were compared. This allows the identification of proteins potentially involved very early in recognition, signalling and defence reactions. In mature M. truncatula mycorrhiza, sub-cellular proteomic approaches were developed to target: i) symbiosis-related membrane proteins eligible as involved in nutrient transport and signalling between symbionts upon arbuscule functioning and ii) very recently, symbiosis-related plastid proteins. In addition, to determine the overlaps in response to the 2 most commonly employed AM fungal isolates (Glomus mosseae and G. intraradices), we recently launched a high throughput comparative proteomic analysis. The future release of the genome sequencing programs launched for M. truncatula and G. intraradices is likely to provide additional knowledge about AM symbiosis-related proteins.