Objective: It is known that there are some biological and neuro-endocrine differences between positive and negative schizophrenia. This study was designed to compare with hypothalamopituitary-thyroid (HPT) axis findings in schizophrenic patients with positive and negative symptoms. Method: 10 patients with positive symptoms and 11 with negative symptoms, and 21 healthy control (HC) subjects were included to the study. Thyroid hormones (free and total T3 and T4 levels), TSH responses to TRH and PRL, and Dmax TSH values were used to evaluate HPT axis functions. Results: No significant differences were found between patients with positive and negative symptoms in terms of HPT axis functions. However, mean thyroid hormone levels, which remain in normal ranges, of the patient groups were significantly higher than those of the healthy controls. The rates of blunted TSH responses to TRH in patients with positive and negative symptoms are 40% and 45%, respectively, and these rates were significantly higher than those of the controls (0%). Basal PRL and PRL responses to TRH levels of the patient groups were similar, but higher than the those of healthy subjects. Conclusions: These findings show that no significant differences in HPT axis functions between patients with positive and negative symptoms; and suggest that the mechanisms, which are related to pathophysiologia of the positive and negative symptoms, may be similar, at least, in terms of some neurotransmitters that related HPT axis functions.