There is currently little information available on calcium-soil-ectomycorrhizal (ECM) interactions. However, for decades calcareous amendments have been made in forest soils subject to acid rain in Europe without any clear knowledge of their impact on ECMs and the roots of their host plants. We have therefore performed a review to assess the impact of Ca associated to calcareous amendments in the soil-ECM-host plant system, which has highlighted: (1) the influence of Ca and its salts (carbonates and oxalates) of biological origin in ECM fungal communities; (2) the impact of Ca on the growth patterns of the host tree roots; (3) the importance for the plants of the rock-eating processes associated to ECMs; and (4) the impact on ECMs of the soil Ca cycle (associated to the litterfall). A greater knowledge of the cause-effect relations between Ca and the soil-ECM-plant system in Mediterranean and temperate forests could have positive repercussions on reforestation projects, actions associated to soil management, the commercial production of ECMs, and the economy of different rural zones in these forest areas.