Existing methods of pulse oximetry rely on a calibration curve for the estimation of oxygen saturation in arterial blood (SpO2). A novel method of computation of SpO2 that does not require the use of a calibration curve is presented in this paper. Based on a model proposed here for the propagation of light through skin, tissue, bone and blood, suitable processing steps are identified so that the analytical expression derived for the estimation of SpO2 becomes free of patient and sensor dependent parameters. Experimental results presented herein establish the efficacy of the proposed method. ©2008 IEEE.