AIM: Permanent hypoparathyroidism is the most common long-term complication after total thyroidectomy. The aim of the present study was to investigate the risk factors of this complication. MATERIAL AND METHODS: Patients undergoing thyroidectomy in our Unit between January 2017 and February 2018 were retrospectively analysed. They were divided into 2 groups: those with normal parathyroid function in the long term were included in Group A, those who developed permanent hypoparathyroidism in Group B. RESULTS: Two hundred and eighty-five patients were included in this study: 271 in Group A and 14 in Group B. No statistically significant difference was found in terms of sex, age, extent of surgery, rate of retrosternal goiter, postoperative stay and histopathological findings between the 2 groups. On the contrary, mean operative time, rate of patients with PTH values < 6.3 pg/mL on postoperative day 1 and mean thyroid weight were significantly greater in Group B than in Group A (P = 0.049, P < 0.001, P = 0.014; respectively). CONCLUSIONS: Long operative times, PTH levels < 6.3 pg/mL on postoperative day 1 and high thyroid weight have proved to be strong risk factors of permanent hypoparathyroidism after total thyroidectomy. Thus, in these cases a careful follow-up is highly recommended.