Abstract: Tc m SPECT thyroid two-phase images of primary hypothyroidism are evaluated in 87 patients in order to provide a basis for clinical diagnosis. Both blood flow and static uptake concordant decrease are observed in 38(44%) cases. Both blood flow and static uptake concordant increase, and uniform in distribution as well are observed in 11 younger patients. 3 patients show normal results. The results suggest that the typical image of 99 Tc m SPECT for primary hypothyroidism is the concordante decrease of both blood flow and static uptake. While a few younger patients' image looked like hyperthyroidism, then differential diagnosis needed to be done by closely connecting with clinical.