Electronic Journal of Differential Equations, Vol. 2009(2009), No. 127, pp. 1-9. Title: Positive solutions for a system of nonlinear boundary-value problems on time scales Author: A. Kameswara Rao (Andhra Univ. Visakhapatnam, India) Abstract: We determine the values of a parameter $\lambda$ for which there exist positive solutions to the system of dynamic equations $$\displaylines{ u^{\Delta \Delta}(t)+\lambda p(t)f(v(\sigma(t)))=0,\quad t\in[a, b]_\mathbb{T}, \cr v^{\Delta \Delta}(t)+\lambda q(t)g(u(\sigma(t)))=0, \quad t\in[a, b]_\mathbb{T}, }$$ with the boundary conditions, $\alpha u(a)-\beta u^{\Delta}(a)=0$, $\gamma u(\sigma^2(b))+\delta u^{\Delta}(\sigma(b))=0$, $\alpha v(a)-\beta v^{\Delta}(a)=0$, $\gamma v(\sigma^2(b))+\delta v^{\Delta}(\sigma(b))=0$, where $\mathbb{T}$ is a time scale. To this end we apply a Guo-Krasnosel'skii fixed point theorem. Submitted July 6, 2009. Published October 04, 2009. Math Subject Classifications: 39A10, 34B15, 34A40. Key Words: Dynamic equations; eigenvalue intervals; positive solution; cone.