Introduction - Thyroid disorders and morphological thyroid abnormalities, such as goiters and nodules, have been identified as potential risk factors for thyroid cancer. Our study aimed to estimate the incidence of these conditions among middle-aged adults in France. Methods - Biological and clinical data collected as part of the SU.VI.MAX cohort (men aged 45–60 and women aged 35–60 at enrollment) were used. Incidence was estimated separately for biological and morphological events. Results - The overall incidence of thyroid disorders was estimated at 2.0%, with hypothyroidism accounting for 1.3% over a mean follow-up of 7.5 years. Our results show that after age 45, women were more affected by thyroid diseases than men. After a mean follow-up of 7 years, the overall incidence of morphological abnormalities was estimated at 4.6%, with that of nodules amounting to 3.9%. Conclusion - This study shows that thyroid diseases occur frequently in the general adult population in France. Among other things, it will enable the identification of potential excess risks of thyroid disorders at the local level. (R.A.)