Physiology changes of the pleura in spontaneous pneumothorax (SP) patients are not known with its etiology remaining unclear. The aim of the study was to investigate the pleural electrophysiology profile of SP patients and to compare it with the normal pleural electrophysiology. Specimens from nine patients who underwent surgery for persistent SP were obtained after wedge resection (apical visceral) and apical pleurectomy (apical parietal) alongside with parietal specimens over the 8th-9th rib (caudal parietal). Specimens were mounted in Ussing chambers and trans-mesothelial resistance (R(TM)) was determined as a permeability indicator. Amiloride (Na(+) channel inhibitor) was used as an ion channel transportation inhibitor. R(TM) of apical visceral, apical parietal and caudal parietal pleura of SP patients was increased (P=0.042, 0.025 and 0.001, respectively) when compared to disease-free specimens obtained from lung lesion patients. Amiloride was unable to increase R(TM) in all cases. Histopathology of apical and caudal parietal specimens revealed inflammatory infiltration. In conclusion, pleural electrophysiology is altered in SP patients when compared with the electrophysiology of disease-free specimens. A similar observation was made for caudal pleura suggesting diffuse process that possibly involves inflammation as shown by the histopathology.