Organization of organelles in muscle cells results from its ultrastructural adaptation to fulfil specific contractile functions. From the aspect of spatial relations among organelles, the organellar neighbouring can be characterized by a new stereologic parameter the environment of organelle. The environment of dyadic elements was analysed using the stereological method of vertical sections applied to electron microscopic images of ventricular muscles of mice. The analysis of the environment of t-tubules revealed that 24% of its surface is open to the free cytosol, whereas 58% of the t-tubule has direct communication with terminal cisterns of the sarcoplasmic reticulum; 9% is in the vicinity of myofilaments and 6% of the surface presents direct contacts with mitochondria. The analysis of the environment of terminal cisterns showed that the surface exposed to the cytosol present 32%, while 38% of their surface is in the vicinity of t-tubules. The cisternal surface interacts by 15% with mitochondria and by 13% with myofilaments. The results of analysis showed that despite of the localization of dyadic complexes in the intermyofibrillar space there is a substantial extent of their interaction with mitochondria that can be of significance for the energetics of cardiac muscle cells.