Electronic Journal of Differential Equations, Vol. 2004(2004), No. 105, pp. 1-6. Title: Stability properties of non-negative solutions of semilinear symmetric cooperative systems Author: Imre Voros (Eotvos Lorand Univ., Budapest, Hungary) Abstract: We investigate the stability of non-negative stationary solutions of symmetric cooperative semilinear systems with some convex (resp. concave) nonlinearity condition, namely all second-order partial derivatives of each coordinate being non-negative (resp. non-positive). In these cases, we will show following [8], extending its results, that this along with some sign condition on the non-linearity at the origin yields instability (resp. stability). Submitted May 25, 2004. Published September 8, 2004. Math Subject Classifications: 35K57, 35B35. Key Words: Cooperative semilinear system; positive stationary solutions.