The association between differentiated thyroid carcinoma (DTC) and chronic lymphocytic thyroiditis (CLT) has been reported in literature.To evaluate the incidence of this association and to determine whether the CLT may influence on the early initial staging of DTC when associated with other variable risks.Historical (retrospective) cohort.Fifty two patients with DTC were evaluated from 1999 to 2009. They were divided into two groups. The first group had 35 patients with DTC without DLT; the second had 17 patients with CLT. Total thyroidectomy was the treatment chosen for all patients. Similarities shared in both groups such as age, gender, histological tumor type, tumor diameter, regional only or with distant metastases, extrathyroidal invasion, multifocality and presence of tumor capsule were considered. T-Student tests and Chi-square tests were applied to analyze the data.The incidence of DTC without CLT was higher that of DTC+CLT (p = 0.0126). We noticed no statistic differences between the common variables analyzed.CLT occurred in 33% of the patients with DCT. All cases of DTC were in the early stages.