Enhanced fruit and vegetable consumption is closely related to reduced cancer incidence as shown in epidemiological studies. Ganoderma lucidum, one of the most well-known traditional Chinese medicines, has been demonstrated to have pharmacological activities and antitumor effects, in Asian populations. However, the promotion of immune responses in normal BALB/c mice is unclear. In the present study, we investigated the immune responses of BALB/c mice after treatment with G. lucidum extract in vivo. The results demonstrated that G. lucidum extract was able to promote the proliferation of splenocytes under Concanavalin A or lipopolysaccharide stimulation. Compared with the control group, phagocytosis of macrophage was significantly enhanced by intraperitoneal administration of G. lucidum extract at both 3 and 6 mg/kg. Compared with the control group, natural killer cell activity was significantly enhanced by intraperitoneal administration of G. lucidum extract (6 mg/kg). Results of cytometric bead array and flow cytometry indicated that the expressions of interleukin-6 and interferon-gamma also increased (p<0.001) by treatment with G. lucidum extract (3 and 6 mg/kg). In conclusion, the findings of this study implied that G. lucidum extract was able to effectively promote immune responses in BALB/c mice.