The aim of this retrospective study is to analyze the risk factors of morbidity in thyroid surgery. From January 1997 to December 2001, 343 patients (69 males and 280 females, mean age 46.1) who underwent surgery under general anesthesia for thyroid disease were analyzed. In 22 (6.4%) cases the operation was a second thyroidectomy. The mean post-operative stay was 2 days (range: 1-7) and the mean follow-up was 21 months (range: 1-60 months). Statistical analysis of our data was performed by chi-square test and confirmed by Fisher exact test. The statistical analysis showed the significance of malignancy and re-surgery as risk factors of hypoparathyroidism and recurrent laryngeal nerve palsy. Sex, age, and type of operation had no influence on the medical records. The completion of thyroidectomy and histological malignancy increase the morbidity of thyroid surgery.