We analyze the competition between high-temperature superconductivity (SC) and antiferromagnetism (AF) using the extended Hubbard model containing following matrix elements in the Hamiltonian: Hund's on-site field F H , singlesite Coulomb repulsion U ¼ ði; ij1=rji; iÞ; two-site charge-charge, exchange, pair exchange and assisted hopping interactions V ¼ ði; jj1=rji; jÞ; J ¼ ði; jj1=rjj; iÞ; J 0 ¼ ði; ij1=rjj; jÞ; Dt ¼ ði; ij1=rjj; iÞ: In our model, we introduce the possibility of AF ordering by dividing the crystal lattice into two interpenetrating sub-lattices a; b: We use Hartree-Fock (H-F) approximation for all interactions except the strong on-site Coulomb repulsion. The self-energies S s g ðÞ (g ¼ a; b) are calculated within the coherent potential approximation (CPA). To obtain the SC transition temperature T C and the Ne´el's temperature T N we solve the coupled equations of motion for the Green's functions. We present numerical results. They show that the AF at half-filling destroys the superconductivity of the s 0 -wave symmetry. Increase of the Coulomb repulsion in the CPA causes increasing dumping of s 0 -wave SC, shifts it away from the halffilling point, enhances SC temperature for sub-lattice magnetic moments; 0omo0.28m B .