Specific granules in atrial heart muscle cells were examined in normal and treated rats with the histochemical method and electron microscopy. These granules were not stained with routine staining method as azan, but when epon embedded sections were stained with toluidine blue, these granules in sarcoplasm along the nucleus were stained well. With Falck-Hillarp method, atrial muscle cells did not show any fluorescence. By the administration of 5-OHDA and 6-OHDA, false transmitters of catecholamine, the shape and the distribution of granules and the electron density of the core of granules did not change, and any fluorescence was not found with Falck-Hillarp method. The administration of 15% alchohol per os for 20 days increased the number of granules in sarcoplasm along the nucleus slightly and after 60-100 days, these granules increased also in sarcoplasm under the cell membrane or between the myofibrils. These results show that specific granules in atrial heart muscle cells do not contain catecholamine. The function of these granules is also discussed in respect to the result obtained with alchohol administration.