The　formation　energy　of　the　mono-vacancy　and　both　the　formation　energy　and　binding　energy　of　the　di-and　tri-vacancy　in　BCC　alkali　metals　and　transition　metals　have　been　calculated　by　using　the　modified　analytical　embedded-atom　method　(MAEAM).　The　formation　energy　of　each　type　of　configuration　of　the　vacancies　in　the　alkali　metals　is　much　lower　than　that　in　the　transition　metals.　From　minimum　of　the　formation　energy　or　maximum　of　the　binding　energy,　the　favorable　configuration　of　the　di-vacancy　and　tri-vacancy　respectively　is　the　first-nearest-neighbor　(FN)　or　second-nearest-neighbor　(SN)　di-vacancy　and　the　[112]　tri-vacancy　constructed　by　two　first-and　one　second-nearest-neighbor　vacancies.　It　is　indicated　that　there　is　a　concentration　tendency　for　vacancies　in　BCC　metals.　(c)　Versita　Warsaw　and　Springer-Verlag　Berlin　Heidelberg.　All　rights　reserved.