Electronic Journal of Differential Equations, Vol. 2011 (2011), No. 133, pp. 1-9. Title: Limit cycles and bounded trajectories for a nonlinear second-order differential equation Author: Henry Gonzalez (Obuda Univ., Hungary) Abstract: In this article, we determine the trajectories of maximum deviation, and the closed trajectories of maximum deviation for nonlinear differential equations of the form $$ \ddot y+2a(t,y,\dot y) \dot y+b(t,y, \dot y)y=c(t,y,\dot y) $$ where the coefficients and the right-hand side are piecewise continuous functions in $t$ and continuous in $y,\dot y$. Also we find necessary and sufficient conditions for the boundedness of all the trajectories. Submitted April 15, 2011. Published October 13, 2011. Math Subject Classifications: 34C05, 70K05. Key Words: Ordinary differential equations; phase plane analysis; limit cycles; maximum deviation trajectories.