The goal of this study was to investigate the influence of experimentally induced hypercalcaemia (after 100000 UI Vigantol and CaCl2) on neuroendocrine cells (NECs) in the thyroid and airways in the rat. After 24 h, 7 days and 14 days the thyroid and lungs were collected. Paraffin sections were immunocytochemically stained with specific antibodies against CGRP, calcitonin (CT) and synaptophysin (SY) in the airway NECs and thyroid C cells. The largest hypercalcaemia were observed in experimental rats after 7 days. More significant changes in the number and size of neuroendocrine cells were observed in the thyroid gland as well as in the airways. In the airways only a slight increase in the number of neuroepithelial bodies (NEBs) was observed, some of which gave evidence of hypertrophy symptoms.