Copyright © 2010 Yuzhen Bai and Lihua Liu. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We establish the oscillation and asymptotic criteria for the second-order neutral delay differential equations with positive and negative coefficients having the forms and . The obtained new oscillation criteria extend and improve the recent results given in the paperof B. Karpuz et al. (2009).