The authors consider the following second order differential equation \[ (1)\quad \frac{d^ 2}{dt^ 2}[y(t)+P(t)y(t-\tau)]+Q(t)y(t- \sigma)=0,\quad t\geq t_ 0,\quad \tau,\sigma \geq 0 \] with \(P,Q\in C([t_ 0,\infty],{\mathbb{R}})\), where the highest derivate of the unknown function appears both with delays \(\tau\) and \(\sigma\) in some terms and without delays in some others. Such equation is called neutral delay differential equation. In this paper the authors investigate the asymptotic behavior of the nonoscillatory solutions of (1) and find sufficient conditions for the oscillation of all solutions; of all bounded solutions; all unbounded solutions.