Abstract: The uptake characters of ⁹⁹Tc^m-MIBI in two lung cancer cell lines (human small cell lung cancer H446 cells and human lung adenocarcinoma SPC-1 cells) were investigated. The uptake kinetic data show that H446 cells absorb significantly higher level of ⁹⁹Tc^m-MIBI comparing with SPC-1 cells. The uptake percentage of ⁹⁹Tc^m-MIBI in H446 cells increases time-dependently and reaches its peak value at about 120 min, and then droppes slowly. This uptake in H446 cells is positively correlated with the number of cells while negatively with the concentration of radiolabelled ⁹⁹Tc^m-MIBI. Furthermore, it is markedly inhibited by excessive unlabelled MIBI. However, the uptake of ⁹⁹Tc^m-MIBI in SPC-1 cells maintains at low levels without a visible peak during the experiment time. These results suggest that the uptake characters of ⁹⁹Tc^m-MIBI are different in two lung cancer cell lines, which is accordant with the clinical facts that patients with lung cancers displayed diverse ⁹⁹Tc^m-MIBI imaging patterns.