A study was conducted to examine the changes in polarized light of three tissues (liver, muscle and skin) with different polarization properties. In a collimated transmission experiment the incident beam was sequentially oriented parallel, perpendicular, 45 degrees to the optical table, and circularly polarized. Optic elements in front of the detector successively selected these four polarization states for each incident beam. The multiply scattered light was not collected. Data were analyzed with the Mueller matrix formalism.