Plant-plant facilitation is an ecological process occurring in most terrestrial ecosystems. Plant-plant facilitation is considered as a positive interaction between both plant partners in which one plant species promotes the growth, survival or reproduction of the neighbouring plant. Recent studies have underlined the role of mycorrhizal fungi, i.e. arbuscular mycorrhizal fungi (AMF) and particularly extra radical hyphae of AMF, in interconnecting plants and consequently their importance in plant-plant facilitation process. Networks of AMF impact soils both physically and biologically and are considered as an important pathway for the transference of nutrients such as nitrogen and phosphorus. In parallel, AMF increase plant growth and nutrient uptake and decrease the deleterious effects of pathogens and drought. The aims of this chapter are to describe how the AMF are involved in the plant facilitation process and to assess the main mycorrhizal effects on the plant nutrition (P and N) and plant health. Also the contribution of AMF in cropping systems as well as agricultural strategies which improve AM associations in arid agrosystems will be reviewed and illustrated by experimental results from field studies in Mediterranean environment.