Algorithms proposed by G. Passarino et al. in "All-purpose numerical evaluation of one-loop multi-leg Feynman diagrams" (Nucl.Phys. B650 (2003) 162-228, hep-ph/0209219) will be detailed. This new technique provides a fast and reliable way to integrate numerically one-loop integrals up to six points. It can be used in all kinematical configurations, especially in the neighbourhood of the (possibly) singular points. Moreover, the introduction of complex masses is allowed.