Using ovarian cancer cell lines, we studied relationship between C-erbB2 expression and lysis activity of lymphokine-activated killer cells (LAK) and in vitro regulation by ?-interferon (IFN-?). The results showed that C-erbB2 overexpression was associated with resistance to lysis activity of LAK in ovarian cancer; IFN-? could reduce the overexpression of C-erbB2 and increase lysis activity of LAK on ovarian cancer cells in which C-erbB2 were overexpressed.