ABSTRACT: The granites showing textures of plagioclase-mantled alkali feldspar megacryst are known as "Rapakivi Granites". Rapakivi granites are generally Proterozoic (1.8 to 1.0 Ga) in age, and Southern Finland is the type area ofthe rapakivi granites although they are preseni in Ukraine the Baltic countries, South Greenland, mid-continental and western USA, Venezuela, Brazil, Botswana and several other Precambrian shield areas. Rapakivi granites are shallow level, multi-phctsc batholiths and stocks, having less than 10 km thick horizontal sheet-like bodies. The magmatic association of rapakivi granites is bimodal. The mafic members are represented by diabase dykes, gabbroids and anorthosites and thefelsic members by A-type granites, syenites and ryholites. The oldest rapakivi granites are generally hornblende-biotite granites whereas the youngest ones are topaz-bearing alkali feldspar granites. in these rocks, plagioclase (andesine or oligoclase), orthoclase, microcline, quartz, hornblende and biotite are present as well as accessory fluorite, anatase, zircon andilmenite. The rapakivi granites are generally metaluminous or marginally peraluminous rocks, and have high Fe/(Fe+Mg). They show chemical characteristics of within-plate granites and A-type granites, and have high K andNa contents. Furthermore, they have higher Si, K, FRb, Ga, Zr, Hf, Th. U, Zn and REE contents andK/Na, Ga/Al, Fe/Mg ratios, andlower Ca, Mg, Al, P and Sr abundances than granitte rocks in general. Theformation of rapakivi granites of Finland can best be interpreted by the mafic under-plate model. Mantle-derived mafic magmas intruded at the mantle-crust boundary and in to lower crust, and caused extensive partial melting ofthe deep crust, thus forming the rapakivi granites. The tectonic settings, bimodal magmatic association, geochemistry and isotope geology of the rapakivi granites can best be explained by mafic underplating, but the reasonfor the mantle melting remains largely open.