Abstract : Symbolic execution is a classical program testing technique which evaluates a selected control flow path with symbolic input data. A constraint solver can be used to enforce the satisfiability of the extracted path conditions as well as to derive test data. Whenever path conditions contain floating-point computations, a common strategy consists of using a constraint solver over the rationals or the reals. Unfortunately, even in a fully IEEE-754 compliant environment, this leads not only to approximations but also can compromise correctness: a path can be labelled as infeasible although there exists floating-point input data that satisfy it. In this paper, we address the peculiarities of the symbolic execution of program with floating-point numbers. Issues in the symbolic execution of this kind of programs are carefully examined and a constraint solver is described that supports constraints over floating-point numbers. Preliminary experimental results demonstrate the value of our approach.