Four patients were subjected to sialolithotomy of the submandibular gland in the Department of Otolaryngology, Collegium Medicum, Jagiellonian University in Cracow. The resected calculi were examined under a scanning electron microscope and chemical analysis of their structure was carried out. Results of these studies were compared with clinical observations. It has been found that sialoliths are built up by inorganic salts, mainly calcium compounds. Crystallization processes proceed at variable rates and are related to duration of the disease and intensity of inflammatory reaction.