Mesoangioblasts (MABs) are mesoderm-derived stem cells, associated with small vessels and originally described in the mouse embryonic dorsal aorta. Similar though not identical cells have been later identified and characterized from postnatal small vessels of skeletal muscle and heart. They have in common the expression of pericyte markers, the anatomical location, the ability to self-renew in culture, and to differentiate into various types of mesodermal lineages upon proper culture conditions. Currently, the developmental origin of MABs and the relationship with other muscle stem cells are not understood in detail and are the subject of active research. This chapter provides an outline of the latest techniques for isolation and characterization of adult MABs from human and mouse skeletal muscles.