Six cases of silent thyroiditis are described. Clinical, analytical, therapeutical and prognostical features are reviewed.Descriptive and retrospective study.Outpatient endocrinological clinic of a General HospitalSix women (age 26-41 years) that fulfil clinical and analytical criteria of silent thyroiditis. In 4 patients thyroiditis was diagnosed in the postpartum period and in the remaining 2 there was no relationship with pregnancy.Serum levels of thyroid hormones and thyroglobulin and thyroid peroxidase antibodies were measured in all patients. Follow-up period was between 12 and 41 months. The 2 patients with the sporadic form of silent thyroiditis showed clinical and analytical data of thyrotoxicosis that spontaneously resolved. The remaining 4 patients presented with hypothyroidism. In one of them the hypothyroidism spontaneously resolved, in 2 it became permanent and in a further one it developed to subclinical hypothyroidism.Silent thyroiditis (sporadic or postpartum) is a frequent disorder, usually benign and transient. It can present in different clinic forms and evolve to resolution of permanent thyroid dysfunction.