Introduction: Given the frequent association between thyroid hormones and emotional symptoms, the aims of this research were to check the occurrence of depressive symptoms in patients with primary hypothyroidism, to study the reversibility of such symptoms after LT4 treatment and to evaluate the existence of predictive symptoms of response/no-response to LT4 only treatment. Methods: 70 primary hypothyroidism female patients (TSHmean: 16 uU/m0l) were assessed with Beck Depression Inventory (BDI).They were all treated solely with LT4. TSH value was tested after treatment and patients who had previously shown depressive symptoms were re-assessed with BDI. Results: 51.4% showed depressive symptoms prior to treatment (TSH: 20.1 uU/ml SE: 4.7; BDI: 23.8 SE: 1.1), 75% of those patients showed no symptoms after LT4 treatment (TSH: 1.63 uU/ml SE: 0.28; BDI: 8 SE: 1), but in the remaining25% those symptoms persisted (TSH: 1.25 uU/ml SE: 0,29; BDI24 SE: 2). Sleep disturbance, item 16, is the only factor with significant persistence (p. ≥ 0.045) after treatment. Conclusions: 51.4% of the hypothyroidism patients showed depressive symptoms; hypothyroidism treatment was adequate to normalize TSH values in all the cases and to reverse depressive symptoms in 75% of them while 25% remain with depressive symptoms. Within this group, the persistence of sleep disturbance could be considered to be a predictive, no-response symptom and would point to the need to re-evaluate diagnosis and to consider the addition of another treatment.