Comprehensive examinations of 92 patients with various forms of chronic sialadenitis revealed similar changes in the salivary glands (SG) with obvious signs of sialadenitis and in the contralateral glands. Many changes in SG which were previously interpreted as sialadenitis are primary signs of sialadenosis. Ductal, parenchymatous, and interstitial forms of sialadenosis correspond to previous ductal, parenchymatous, and interstitial forms of sialadenitis. Common, relative, and absolute signs of diseases are defined, which allow differential diagnosis between various forms of sialadenitis and sialadenosis.