The follow-up of initially non suspect thyroid nodules after fine needle biopsy is not completely worked out. Since 1985, we have entered upon a prospective study concerning the followup of thyroid nodules supposed to be benign after initial evaluation. What are the nature and the frequency of means to be used for their follow-up? Three hundred and eleven nodules are followed up on a mean duration of 2.44 years. The follow-up of 65 of them is 4 years or more. The follow-up of 120 others is 3 to 4 years; 197 nodules are followed up during 2 to 3 years. A physical examination, an ultrasonography completed with a fine needle biopsy or an ultrasonically guided fine needle biopsy are worked out every year. Twenty-three per cent of initial biopsies are non significant and 90% of them are ultrasonically guided biopsies. At the end of the study, the repeating biopsies reduce to 6% the non significant biopsies ratio. Four histological thyroid cancers are detected in three female patients 1 year, 2 years and 5 years after the initial evaluation. Ultrasound alterations of nodules are observed in case of very suspect biopsies. Ninety-six per cent of the followed up thyroid nodules remain not cytologically suspect. These findings allow us to propose the following guidelines for the assessment of a non suspect thyroid nodule: half-yearly or yearly physical examination, yearly or biennial ultrasonography, repeat biopsy after 2 or 3 years when clinical or ultrasound suspect modification is wanting.