Polarization-sensitive optical coherence tomography (PS-OCT) has been used to extract polarization properties of four different diseased lungs ex vivo, including fibrotic sarcoidosis (FS), chronic obstructive pulmonary disease (COPD), fibrotic extrinsic allergic alveolitis (fibrotic EAA) and cystic fibrosis (CF). An increase in alveoli size has been observed in COPD lungs. Furthermore, an increase in birefringence signal was observed for FS and fibrotic EAA. In CF, a few areas with thick patches of birefringence occurred. The results show potential of in vivo assessment of lung fibrosis. Histology slides of all lungs were acquired, and will be used to further interpret the results.