Alternative and complementary medicine are widely used in treating children with cancers. A population-based survey in British Columbia revealed that they were used by 42% of the respondents. Among Chinese in Hong Kong, Traditional Chinese Medicine (TCM) is also widely practiced. Some 60% of the population had consulted TCM practitioners at one time or another. TCM use could be dated back to more than five thousand years ago, and written records were available for over two thousand years. TCM is considered to be an integral part of the Chinese culture. In our experience, TCM is believed to be commonly used to 'strengthen immunity and promote health' among local children with cancers, despite the lack of well-designed study to prove its usefulness. Ganoderma lucidum (Ling Zhi) is a mushroom long-used in China for a broad range of disorders. Its use is common in the general population and among both adults and children with a wide range of malignancies. However, there is no randomized controlled trial to support its clinical efficacy and safety. Therefore, we conducted this clinical trial of Ganoderma lucidum (Ling Zhi) among Hong Kong children with cancers.