Aim. A residual mediastinal thyroid (“forgotten goiter”) is a well-known, though uncommon, complication of total thyroidectomy. Materials of study. The authors analyze their experience with three cases of goiter forgotten, observed in a series of 2946 thyroid resections in the period 2005–2010. In the study, a preoperative CT of the chest with three-dimensional reconstruction was always performed to examine the topographical relationships of the lesion. Excision was performed through cervicotomy, cervicosternotomic approach and cervicosternotomy, and posterolateral right thoracotomy. Results. There were no complications. Histological examination was suggestive of malignancy in one case (follicular carcinoma with pulmonary metastases). Discussion. The indication for surgery in cases of forgotten goiter is intrinsic to the diagnosis. Preoperative evaluation with accurate topographic imaging is required in all cases in order to understand the nature and location of mediastinal pathological tissue and to identify the most suitable access route. The cervicotomy is the ideal access for low surgical trauma and is easily extendable into a partial or complete sternotomy. A thoracotomy, on the other hand, which is usually reserved for the right side, must be planned preoperatively.