The multiresolution representation given by the wavelet decomposition of monodimensional and bidimensional signals is assuming more and more importance in the field of digital signal analysis. The scheme used to obtain the wavelet decomposition of a digital signal closely resembles the subband decomposition scheme: the main difference is in the way the analysis and synthesis filters are calculated. FIR and IIR implementations are possible, the latter being more efficient from the point of view of computational cost. In the Letter an IIR implementation of a wavelet decomposition is presented.