This paper presents a new numerical algorithm based on interval analysis able to prove that a differentiable function f : A subset of R-n --> R-n is injective. This algorithm also performs a partition of the domain A in subsets A(i) where, for all x is an element of A(i), the cardinality of f(-1) (f(x)) is constant. In the context of parameter estimation, we show how this algorithm provides an efficient and numerical method to study the structural identifiability of parametric models. (C) 2008 Elsevier Ltd. All rights reserved.