Background: Papillary thyroid carcinoma can have familial aggregation. Aim: To compare retrospectively familial non medullary thyroid carcinoma (FNMTC) with sporadic papillary thyroid carcinoma (PTC). Material and methods: Retrospective analysis of medical records of patients with thyroid carcinoma. An index case was defined as a subject with the diagnosis of diffierentiated thyroid carcinoma with one or more first degree relatives with the same type of cancer. Seventeen such patients were identified and were compared with 352 subjects with PTC. Results: The most common affected relatives were sisters. Patients with FNMTC were younger than those with PTC. No differences were observed in gender, single or multiple foci, thyroid capsule involvement, surgical border involvement, number of affected lymph nodes and coexistence of follicular hyperplasia. Patients with FNMTC had smaller tumors and had a nine times more common association with lymphocytic thyroiditis. Five patients with FNMTC had local recurrence during 4.8 years of follow up. Conclusions: Patients with FNMTC commonly have an associated chronic thyroiditis, are younger and have smaller tumors than patients with PTC.