Surfactant-assisted　high　energy　ball　milling　technique　is　a　new　method　of　producing　magnetic　nanoparticles.　In　this　study,　permanent　magnetic　SmCo5　nanoparticles　and　nanoflakes　with　high　room-temperature　coercivity　values　and　narrow　particle　size　distributions　were　produced　by　this　technology　and　a　subsequent　size-selection　process.　The　SmCo5　nanoparticles　with　average　particle　sizes　of　9.8　and　47.5　nm,　exhibited　room-temperature　coercivity　values　of　6.8　x　10(4)　and　7.3　x　10(5)　A/m,　respectively,　while　the　SmCo5　nanoflakes,　with　the　mean　particle　size　of　about　1.4　mu　m　and　average　thickness　of　75　nm,　showed　excellent　permanent　magnetic　properties　with　an　obvious　c-axis　crystal　texture,　a　strong　magnetic　anisotropy　and　high　coercivity　values　of　5.5　x　10(5)　and　1.6　x　10(6)　A/m　in　their　easy-axis　and　hard-axis　directions,　respectively.　The　coercivity　values　of　SmCo5　nanoparticles　and　nanoflakes　exhibited　a　significant　particle　size　dependance　effect.