Electronic Journal of Differential Equations, Vol. 2009(2009), No. 49, pp. 12. Title: Existence and uniqueness theorems on certain difference-differential equations Author: Baburao G. Pachpatte (Aurangabad, Maharashtra, India) Abstract: In the present paper, existence and uniqueness theorems for the solutions of certain nonlinear difference-differential equations are established. The main tools employed in the analysis are based on the applications of the Leray-Schauder alternative and the well known Bihari's integral inequality. Submitted June 9, 2008. Published April 07, 2009. Math Subject Classifications: 34K5, 34K10, 34K40. Key Words: Existence and uniqueness; difference-differential equations; Leray-Schauder alternative; Bihari's integral inequality; Wintner type; Osgood type.