In 168 patients who underwent thyroid surgery due to a goitre the frequency and the temporal occurrence of functional autonomy in recurrent goitres were determined retrospectively. The diagnosis of functional autonomy was established by quantitative suppression scintigraphy with 99mTc. In the region examined the limiting value for functional autonomy is 1.0% 99mTcU after suppression. In 41% (n = 69) of the patients a recurrent goitre was found in the clinical examination. The postoperative observation period in this patient group ranged from 2 months to 42 years with an average of 13.8 years. Whereas the prevalence of functional autonomy in the early postoperative years was low, a continuous increase of thyroid autonomy with values of about 4% per year could be found until the 20th postoperative year, the rate of patients with functional autonomy was then about 70%. Thereafter the prevalence of thyroid autonomy increased only marginally and reached about 90% in the 40th postoperative year. The results demonstrate that functional autonomies in recurrent goitres are frequent. The majority of examined patients had recurrent and not residual autonomies.