Ganoderma lucidum (Lingzhi) is a Traditional Chinese Medicine which is widely used as a means to 'strengthen immunity' among patients with cancers. However, there is no published randomized controlled clinical trial on its efficacy and safety despite the many in vitro studies on its anti-viral, anti-oxidative, anti-tumour, radioprotective, hepato-protective and immunomodulatory effects. This study was a randomized, double-blind, placebo-controlled, parallel clinical trial that investigated the benefits and safety of Ganoderma lucidum (Lingzhi) in treating children with cancers. Patients were randomized to receive identical capsules of either Lingzhi or placebo for six months. The primary outcome was the general Paediatric Quality of Life score. Secondary outcomes included immune functions, infection-related morbidities, complete blood counts and serum biochemistry, and overall and event-free survival.