The paper deals with the theory of differential-functional inequalities and with its applications to mixed problems for first order partial differential-functional equations with initial-boundary conditions.The theory of partial differential inequalities was originated by Haar [5] and Nagumo [13]. The classical theory of partial differential inequalities is in detail described in monographs [9], [15]. The main applications of the theory concern questions such as: estimates of solutions of partial equations, estimates of the difference between solutions of two initial problems, estimates of the existence domain of solutions, criteria of the uniqueness of the solutions, stability criteria, estimates of the error for an approximate solution, continuous dependence of the solution on initial data and on the right hand side of the system. A similar role in the theory of differential-functional equations with the first order partial derivatives is played by ordinary differential-functional inequalities. Some results in this field can be found in [4], [6], [7], [14]. All results in the papers cited above concern initial value problems for first order partial differential-functional equations.In this paper we consider mixed initial-boundary value problems for differential-functional equations. We prove a theorem on the uniqueness of solutions of Perron type. We obtain this uniqueness theorem as a particular case of some general comparison theorem for differential-functional inequalities with initial-boundary conditions.In the last part of the paper we give a generalization of the well-known theorems on differential or differential-functional inequalities with initial conditions ([9], [14], [15]) on the case of differential-functional inequalities with initial-boundary conditions. Let C(X, Y) denote the class of all continuous mappings from X into Y where X, Y are metric spaces. We shall use vectorial inequalities if the same inequalities hold between their corresponding components. We shall denote a function w of the variable t 9 [c~,fl) C R by (w(t))[a,~). Denote by 11. IIc the supremum norm in theWe introduce the following assumption (see [16]). Assumption H0. Suppose that a region f~ C R l+n satisfies the following conditions:Mathematics subject classification numbers, 1991. Primary 34A40, 34A99, 34B99.