‘Monrepos’ is a Prunus-plum rootstock developed at the Agri-Food Research and Technology Center of Aragon (CITA), Zaragoza, Spain, for use as a rootstock for sweet cherry (Prunus avium L.). Cherry rootstock research over the last decade has been focused more on rootstock evaluation than on breeding new rootstocks (Hrotko, 2008). Initially, dwarfing potential was the main focus for cherry rootstocks breeding programs. However, many challenges remain to be addressed in the areas of adaptation to biotic and abiotic stresses, graft compatibility, and rootstock influence on scion performance and fruit quality. In Spain and other Mediterranean countries, Prunus mahaleb L. (St Lucie) and its clone, SL 64, are widely used as cherry rootstocks in gravelly, well-drained, droughty, and calcareous soils. However, P. mahaleb L. rootstocks are unsuitable on heavy soils or where waterlogging occurs. In heavy soils or when replanting old orchard soils, P. cerasus (CAB series), MxM 14, and Adara (P. cerasifera L.) can reduce the problem of soil fungi in some circumstances (Perez, 2005), although some cherry cultivars are incompatible. New rootstocks suitable for use with sweet cherry are needed to solve the problems of soil adaptation, vigor, and graft incompatibility of the traditionally used rootstocks (Hormaza and Gella, 1996; Sansavini and Lugli, 2008). ‘Monrepos’ was selected from eight initial clones, because it shows good compatibility with a wide range of cherry cultivars, good adaptation to calcareous and heavy soils with high lime content, high productivity, and good rooting aptitude. In a flood-irrigated trial established in calcareous soil, pH 8.3 with active lime content and clay-loam texture, the clone was highly productive. Plants propagate well by in vitro and hardwood cuttings methods that makes it a valuable rootstock for small propagator companies or the largest producers of fruit rootstocks. ‘Monrepos’ offers a better production alternative for cherry cultivars, especially in heavy soils under flood irrigation conditions where other traditional cherry rootstocks fail to survive.