The frequency of medico-legal issues after surgery is rising. Knowledge of the character and frequency of such problems following surgery of the thyroid gland is scant. Analysis of 21,515 cases of adverse effects after medical treatment from 1975 through 1998 identified 222 cases (1 %) of litigation following surgery for thyroid diseases. The frequency of litigation problems rose exponentially during this interval. Malpractice was confirmed in 36 cases (16 %). The litigation was directed against the surgeon in 95 % of cases, the anesthesiologist in 2 %, both of them in 3 % and the ear-nose-throat surgeon in one case. Eighty-nine percent of the 222 cases occurred after routine thyroid surgery. Typical complications such as recurrent nerve palsy (50 %), hypoparathyroidism (14 %), bleeding (3 %), and late goiter recurrence (1 %) accounted for 63 % of the presumed but for only 31 % of ascertained malpractice cases. Atypical complications such as other neurologic deficits (10 %), infections (5 %), residual nodules (4 %), scar problems (5 %) accounted for 37 % of the suspected but for 70 % of confirmed malpractice cases. Deficiencies in obtaining informed consent were present in only 11 %. Malpractice was more frequently judged to be present, if a second operation was necessary (P < 0.001), if the goal of the operation had been missed (P < 0.001), or if any kind of complication was followed by a fault in postoperative care (P < 0. 001).