In　this　paper,　we　establish　some　determinantal　inequalities　concerning　M-matrices　and　inverse　M-　matrices.　The　main　results　are　as　follows:　1.　If　A　=　(a(ij))　is　either　an　n　x　n　M-matrix　or　inverse　M-matrix,　then　for　any　permutation　i(1),　i(2),....　i(n)　of　{1,2,...,n)　(a)　[GRAPHICS]　(b)　det　A　=　Pi(n)(i=1)　a(ii)　if　and　only　if　A　is　essentially　triangular.　2.　If　A　=　(a(ij))　is　an　n　x　n　M-matrix,　B　=　(b(ij))　is　an　n　x　n　inverse　M-matrix,　A　o　B　denotes　the　Hadamard　product　of　A　and　B,　then　A　o　B　is　an　M-matrix,　and　for　any　permutation　i(1),　i(2),...,　i(n)　of　{1,　2,...,　n},　[GRAPHICS]　(C)　2007　Elsevier　Inc.　All　rights　reserved.