A digital filtering system for ECG baseline wandering removal is described in this paper. It is based on techniques of FIR filtering with decimation and interpolation which inherently have no phase distortion. The system has several advantages over the method of curve fitting (specifiable frequency characteristic) and the method of classical filtering (low computation, transients and delay times). A very low amplitude distortion for the low frequency components of the P and T waves is achievable. These advantages together with design details of the system are discussed.