In this paper we study asymptotic behavior of solutions of second order neutral functional differential equation of the form $${\left(x\left(t\right)+px(t-\tau )\right)}^{\text{'}\text{'}}+f(t,x\left(t\right))=0.$$ We present conditions under which all nonoscillatory solutions are asymptotic to $at+b$ as $t\to \infty$, with $a,b\in R$. The obtained results extend those that are known for equation $$u^{\text{'}\text{'}}+f(t,u)=0.$$

We study asymptotic properties of solutions of the system of differential equations of neutral type.