The forced oscillation technique (FOT) measures the respiratory impedance in a noninvasive way to obtain the mechanical properties of a respiratory system. The respiratory impedance (Zrs) is defined by the frequency-dependent ratio of pressure and flow at the airway opening. A major problem when measuring Zrs at low frequencies (0.1-2 Hz) on spontaneously breathing patients is the disturbance generated by the patients breathing (0.1-1 Hz). A method is presented that aims at eliminating breathing disturbances from low frequent FOT measurements by applying a combination of amplitude and phase modulated signal models and regularized least squares. The method is validated on simulations using breathing measurements, and estimates of Zrs with a very low error are obtained. In addition, the method has been applied to measurements performed on a group of healthy subjects, and the results are obtained that can be used for diagnostic purposes or for further studies on parametric modeling of Zrs at low frequencies.