Gambogic acid (GA) is one of the important active ingredients of gamboge. Our study examined the expression of transferrin receptors (TFR) on the cell surface of human lung SPC-A1 and SK-MES-1 cells and measured their GA-induced apoptosis rate. The results showed that SPC-A1 cells with a higher TFR expression were more sensitive at the same GA concentrations. To examine its distribution in cultured cells and study the mechanisms of apoptosis, we labeled GA with a (125)I tracer and examined the expression of apoptosis-related proteins. we found that GA uptake into SPC-A1 cells was higher than into SK-MES-1 cells; apoptosis-related proteins Caspase 2, Caspase 9, Caspase 10, Bax and p53 were involved in GA-induced apoptosis. We conclude that GA has an apoptosis-promoting effect on non small cell lung cancer cells. In clinical practice, the histopathological quantitation of TFR expression levels in tumor tissues may become a predictor of the sensitivity of patients' tumors to GA treatment.