Electronic Journal of Differential Equations, Vol. 2004(2004), No. 41, pp. 1-14. Title: Existence of trivial and nontrivial solutions of a fourth-order ordinary differential equation Authors: Tihomir Gyulov (Univ. of Rousse, Bulgaria) Stepan Tersian (Univ. of Rousse, Bulgaria) Abstract: We study the multiplicity of nontrivial solutions for a semilinear fourth-order ordinary differential equation arising in spatial patterns for bistable systems. In the proof of our results, we use minimization theorems and Brezis-Nirenberg's linking theorem. We obtain also estimates on the minimizers of the corresponding functionals. Submitted January 5, 2004. Published March 23, 2004. Math Subject Classifications: 34B15, 34C25, 35K35. Key Words: Fourth-order ordinary differential equation; variational method; Brezis-Nirenberg's theorem.