The aim of the study was to establish to what degree the 24-week exposure of a rat to 5 and 50 mg Cd/dm3 affects the proliferating activity of cells with PCNA and Ki-67 nuclear immunoreactivity in the submandibular gland cells. The control animals received only redistilled water to drink. The group I rats were given 5 mg Cd/dm3, while the group II animals were given 50 mg Cd/dm3. The highest concentration of cadmium was observed in group II, with a concomitant increase in the number of PCNA-positive cells. In group I, cadmium concentration was significantly less compared to group II, and there were fewer PCNA-positive cells. The reaction for Ki-67 in both experimental groups was negative.