We give sufficient conditions that the homogeneous differential equations : for $t{geq}t_0$(> 0), $$x^{{prime}{prime}}(t)+q(t)x^{prime}(t)+p(t)x(t)=0,\x^{{prime}{prime}}(t)+q(t)x^{prime}(t)+F(t,x({phi}(t)))=0$$, are oscillatory where $0{leq}{phi}(t)$, 0 < ${phi}^{prime}(t)$, $lim_{t o{infty}}{phi}(t)={infty}$. and $F(t,u){cdot}sgn$ $u{leq}p(t)|u|$. We obtain comparison theorems.