Passive electrical properties of rabbit papillary muscle were studied under normal and hypoxic conditions. The input resistance and the lenght of the electrotonic decay were measured. The results obtained suggested that within a frame-work of a two-dimentional model for anisotropic syncytium the resistance of electrogenic membrane displayed a 1.4-fold decrease on the 10th min after the onset of the hypoxic condition: also the longitudinal (sigma x) and the transverse (sigma y) resistances of the intracellular medium of the syncytium increase 1.39- and 1.3-fold, respectively. An increase in the sigma x and sigma y should be ascribed to the increase in the contact membrane resistance. Derangement of the intercellular interaction under hypoxic conditions is of importance for the understanding of the mechanisms operating in the cardiac arrhythmia due to heart ischemia or myocardial infarction.