Background Calcium makes up 1-2⸓ percent of a person’s body weight, and 99⸓ of it can be found in bones and teeth. The remaining circulates in the blood, muscles, and other tissues. Calcium deficient diet affect general health by causing obesity, fat accumulation, diabetes (insulin resistance), osteoporosis and finally bad oral health due to the non- functioning salivary gland caused by hypocalcemia If calcium deficiency is not treated, it is considered a fatal condition. Calcium is used entirely by the salivary gland to induce its secretory function also it acts as a common modulator mediator for all receptors. Calcium deficiency increases fat cell formation and decreases exocytosis. Aim of this study is to investigate the effect of calcium on general health and on the parotid salivary gland structure in rats. Methods: twenty-four adult male albino rats weighting from 150-200 grams were divided into two groups 12 rat each, group I: control, group II: calcium deficient diet. Body weight, general health observations were measured weekly throughout the experimental period while blood serum level of cholesterol, calcium, insulin, and glucose were all measured at the end of the experiment which lasted for 8 weeks. At the end of the experiment, the rats were euthanized, and the parotid glands were dissected, prepared for light and electron microscopic examination. Results: Group II showed obesity, increase in blood cholesterol, insulin, and glucose level. The ultra-structural and histological examinations showed loss of the normal architecture of acini and duct system as well as the capsule. Conclusion: calcium deficient has a toxic effect on general health and on the parotid salivary gland structure.