BACKGROUND Single cases of clinical observations suggest the efficacy of the Viscum album (VA) extract Iscador P in the treatment of follicular B-Non-Hodgkin's Lymphoma (B-NHL). A previously published study aroused a controversial dispute as it indicated that IL-6 serum levels are elevated following i.v. VA treatment. Increased IL-6 levels have been shown to promote the progression of B-cell neoplasia such as B-NHL. Objective of this study was to investigate whether the VA extract influences the expression of IL-6 and its receptor components in follicular B-NHL cell lines. METHODS Follicular B-NHL cell lines (WSU-NHL, DoHH-2) were incubated with clinically relevant doses of VA extract for up to 3 days. At specified time points (6, 24, 48, 72 h) samples were taken and the expression of IL-6 and its receptor components were analysed by real-time-RT-PCR, flow cytometry and ELISA. RESULTS Treatment of follicular B-NHL cell lines with VA extract did not alter the expression level of IL-6 and its' receptor components at any time and with any of the applied VA extract concentrations. CONCLUSIONS Clinically relevant doses of the VA extract do not trigger an autocrine or paracrine IL-6 loop nor do they initiate IL-6 trans-signalling in follicular B-NHL cell lines.