The potential of natural substances with immunotherapeutic properties has long been studied. β-glucans, a cell wall component of certain bacteria and fungi, potentiate the immune system against microbes and toxic substances. Moreover, β-glucans are known to exhibit direct anticancer effects and can suppress cancer proliferation through immunomodulatory pathways. Mortality of lung cancer has been alarmingly increasingly worldwide; therefore, treatment of lung cancer is an urgent necessity. Numerous researchers are now dedicated to using β-glucans as a therapy for lung cancer. In the present attempt, we have reviewed the studies addressing therapeutic effects of β-glucans in primary and metastatic lung cancer published in the time period of 1991–2016.