The aim of the study was to compare the extent of surgery in removal of thyroid tissue and serum calcium values postoperatively.Material and methods. Between January 1 and December 31, 2005, 987 patients were operated on at our department due to various thyroid disorders. Patients with anaplastic, medullary and high-stage highly-differentiated (TNM>T3, N0, M0) thyroid carcinomas, as well as reoperated individuals, were excluded from the investigation. The patients were divided into three groups, depending on their serum calcium values; thus, the authors distinguished groups with mild (2.0-2.19 mmol/l), moderate (1.8-1.99 mmol/l) and severe hypocalcemia (<1.8 mmol/l). Differences between the groups were assessed by statistical methods (the t-Student's test and the X2 test - the STATISTICA software). The value of p<0.05 was accepted as statistically significant.Results. Of 987 surgical patients, 63 (6.4%) were found to have symptomatic or asymptomatic hypocalcemia. The group included 61 females and two males, their mean age being 50.1±12 years. The intensity of clinical symptoms of hypoparathyroidism was positively correlated with serum calcium values and the said symptoms were most clearly seen in patients classified as belonging to group 3 (Ca<1.8 mmol/l). The most common surgically treated thyroid disease was non-toxic nodular goiter. Hypocalcemia was the most frequent finding in patients operated on due to thyroid carcinoma. In all patients with a mild form of hypocalcemia, the onset of clinical symptoms occurred on postoperative day 2. As it follows from the analysis, there were no statistically significant differences in hypocalcemia prevalence between patients subjected to bilateral exposure of the thyroid lobes and subtotal vs. total thyroidectomy (6 (6.1%) vs 24 (7.1%) patients). On the other hand, a statistically significant difference between the lower prevalence rate of hypocalcemia in unilateral procedures (p<0.001) as compared to bilateral neck explorations (4 (1.4%) vs 59 (8.4%) patients) seems to be logical and physiologically justified. In addition, an element that was found to affect the level of calcium deficit was the number of parathyroid glands identified "in situ". Hence, the prevalence of hypocalcemia increased with a decrease in the number of identified parathyroids (p<0.05). In hypocalcemic patients, hospitalization time ranged from 3 to 11 days, with a mean time of 5.3 days as compared to 3 days in patients without complications. Six months after the surgery and pharmacotherapy, no clinical and biochemical signs of hypocalcemia were noted in the above described group.Conclusions. The risk of hypocalcemia following thyroid surgery is higher in bilateral neck explorations. There are no statistically significant differences in postoperative hypocalcemia between patients subjected to bilateral subtotal vs. total thyroidectomies.