Electronic Journal of Differential Equations, Vol. 2007(2007), No. 01, pp. 1-7. Title: On oscillation and asymptotic behaviour of a neutral differential equation of first order with positive and negative coefficients Authors: Radhanath Rath (Khallikote Autonomous College, Orissa, India) Prayag Prasad Mishra (Silicin Inst. of Technology, Orissa, India) Laxmi Narayan Padhy (K.I.S.T, Orissa, India) Abstract: In this paper sufficient conditions are obtained so that every solution of $$ (y(t)- p(t)y(t-\tau))'+ Q(t)G(y(t-\sigma))-U(t)G(y(t-\alpha)) = f(t) $$ tends to zero or to $\pm \infty$ as $t$ tends to $\infty$, where $\tau ,\sigma ,\alpha$ are positive real numbers, $p,f\in C([0,\infty),R),Q,U\in C([0,\infty),[0,\infty))$, and $G\in C(R,R)$, $G$ is non decreasing with $xG(x)>0$ for $ x\neq 0$. The two primary assumptions in this paper are $\int_{t_0}^{\infty}Q(t)=\infty$ and $\int_{t_0}^{\infty}U(t)<\infty$. The results hold when $G$ is linear, super linear,or sublinear and also hold when $f(t) \equiv 0$. This paper generalizes and improves some of the recent results in [5,7,8,10]. Submitted November 2, 2006. Published January 2, 2007 Math Subject Classifications: 34C10, 34C15, 34K40. Key Words: Oscillatory solution; nonoscillatory solution; asymptotic behaviour.