Acetylenic alcohol, panaxydol, isolated from Panax ginseng shows a significant growth inhibitory effect against various types of cultured cell lines. Its anti-proliferative effect is highly specific for malignant cells, but varies by cell lines. In the present study, the relationship between cellular sensitivity to panaxydol and the affinity of panaxydol for target cells was studied. Panaxydol was conjugated to bovine serum albumin (BSA). Panaxydol-BSA was first incubated with sensitive cells, MK-1 cells, or resistant cells, HeLa cells, and then FITC-labeled anti-BSA antibody was added. The percentage of labeled cells and relative mean of fluorescence were determined by flow cytometry. The results indicate that the sensitivity of target cells against panaxydol is partly prescribed by its affinity for target cells.