Disconjugacy and C-disfocality of second-order self-adjoint difference equation

are discussed in this paper, where p(t) is nonzero with same sign on N(a + 1, b + 2) and q(t) is real valued on N(a + 1, b + 1). Some sufficient conditions are obtained explicitly in terms of coefficients, which can be easily verified. These results generalize some known ones in the literature.