The TRH stimulation test was known as a highly diagnostic method in hypothalamo pituitary disorders. To evaluate the location and the extension of the lesion, we estimated TSH response to TRH test in 27 patients. Correlation between volume of sella and TSH response was also studied. The results obtained were 25 follows: 1) In Sheehan's syndrome, TSH response after TRH test were not observed in all of 12 patients. 2) All 2 acromegaly patients showed normal TSH response. 3) In 4 cases of chromophobe adenoma, 2 cases showed no TSH response. In 2 responded cases, one patient whose tumor mass extended to suprasella region was hypothyroid state. 4) In craniopharyingioma 3 cases, the tumor which extended to intrasella showed hypothyroid and no TSH response. 5) Correlation between volume of sella and TSH response were valuable in 2 cases, but no diagnostic significance. 6) In diabetes inspidus, TSH response were all absent. 7) In primary amenorrhea, TSH response observed in 1 case, which conformed with isolated FSH deficiency.