The aim of this study was to evaluate the influence of co-exposure to cadmium (Cd) and ethanol on the structure and function of the thyroid. Male Wistar rats were exposed to 50 mg of Cd/dm3 in drinking water and ethanol in a dose of 5 g/kg body wt/24 h (administered intragastrically in two equal doses for 5 days a week) for 12 weeks. The structure of the thyroid was assessed in a light microscope. Immunohistochemical methods were used to determine calcitonin (CT), the calcitonin-gene related peptide (CGRP), somatostatin (ST) and synaptophysin (SPh) in the thyroid parafollicular cells (C cells). Weakening of the reactions for CT, CGRP, ST, SPh was observed in C cells. The animals, exposed to a combined action of Cd and ethanol, showed signs of enhanced activity (elevated light follicular epithelium and rarefied colloid), as well as features of intensified remodelling (partial or total follicular atrophy and the appearance of new follicles) of the thyroid gland. In some fragments of the connective tissue stroma mononuclear cell infiltration was observed. The nature of the changes, observed in the rats, simultaneously exposed to Cd and ethanol, may suggest an enhancement in the function of C cells.