Radioiodide concentrating activity in the thyroid, mediated by human Na+/I- symporter (hNIS), provides a mechanism for effective radioiodide treatment for patients who have invasive, recurrent, and metastatic thyroid cancers after total thyroidectomy. In an attempt to develop hNIS gene transfer for radioiodide therapy for patients with brain tumors, we have constructed recombinant adenoviruses, rAd-CMV-hNIS9 and rAd-CMV-FLhNIS, to express exogenous hNIS in U1240 and U1240Tag human glioma cells. U1240Tag differs from U1240 glioma cells in that it expresses the SV40 large T antigen oncoprotein. In both U1240 and U1240Tag cells, radioiodide uptake (RAIU) activity in the cells infected with rAd-CMV-hNIS9 or rAd-CMV-FLhNIS increases as the adenoviral MOI increases. The protein expression profile of hNIS in infected cells is generally in agreement with their RAIU activity profile. Although the expressed hNIS9 protein appeared to have a shorter half-life than FLhNIS, hNIS9 expression could be maintained by multiple infections in these cells. In addition, we show that hNIS can be expressed and function in a xenografted human glioma by intratumoral injection of rAd-CMV-hNIS9.