Preclinical studies have established that the polysaccharide fractions of Ganoderma lucidumhave potential an-titumor activity. Recent clinical studies have demonstrated that G. lucidumpolysaccharides enhance host immune functions[e.g., enhanced natural killer (NK) cell activity] in patients with advanced solid tumors, although an objective response wasnot observed. This open-label study aimed to evaluate the effects of water-soluble G. lucidumpolysaccharides (Ganopoly??,Encore International Corp., Auckland, New Zealand) on immune functions in patients with advanced lung cancer. Thirty-sixpatients were enrolled and treated with 5.4 g/day Ganopoly for 12 weeks. In the 30 cancer patients who completed the trial,treatment with Ganopoly did not significantly alter the mean mitogenic reactivity to phytohemagglutinin, mean counts of CD3,CD4, CD8, and CD56, mean plasma concentrations of interleukin (IL)-2, IL-6, and interferon (IFN)-., or NK activity in thepatients, but the results were significantly variable. However, some cancer patients demonstrated markedly modulated im-mune functions. The changes in IL-1 were correlated with those for IL-6, IFN-., CD3, CD8, and NK activity (P. .05), andIL-2 changes were correlated with those for IL-6, CD8, and NK activity. The results suggest that subgroups of cancer patientsmight be responsive to Ganopoly in combination with chemotherapy/radiotherapy. Further studies are needed to explore theefficacy and safety of Ganopoly used alone or in combination with chemotherapy/radiotherapy in lung cancer patients.