Of 287 consecutive patients, surgically treated at our department for benign, nontoxic goitre during a six-year period, 261 could be followed up, on average, 8.0 years postoperatively. Unilateral surgical procedures had been used in 199 patients, subtotal thyroidectomy in 62. 29 patients were treated with thyroxine (T4) immediately postoperatively ("recurrence prophylaxis"); in the other patients thyroxine was only given in cases of hypothyroidism (significant increase of s-TSH). 26 patients had a goitre recurrence 0.5-10 years after surgery; of these 3 had got T4 as "recurrence prophylaxis" and 23 had not. There was no significant difference between patients with and without T4 postoperatively regarding the rate of recurrence. Of 55 patients treated with subtotal thyroidectomy, 33 had postoperative latent (n = 26) or manifest (n = 7) hypothyroidism. Only 13 of 177 patients operated on unilaterally developed hypothyroidism; two of these had Hashimoto's thyroiditis. All cases of hypothyreosis except 4 were detected within the first 12 months of follow-up. This study indicates that routine use of thyroxine as prophylaxis against recurrence after surgery for benign nontoxic goitre can be strongly questioned and that the risk of hypothyroidism is high after subtotal thyroidectomy.