Natural products historically represent a source of clinically approved drugs that have contributed significantly to anticancer drug development. In particular, essential oils represent a group of advantageous anticancer candidates as not only can they be produced in large quantities in a cost-effect manner but they also exhibit minimal toxicity. Melaleuca alternifolia Concentrate (MAC) is an extract prepared from the native Australian plant M. alternifolia (also a common source of Tea Tree Oil). Melaleuca oils are commonly used products, primarily utilised and investigated for their antimicrobial activity. However, over the last 2 decades, a continued stream of evidence has been produced pertaining to the anticancer potential of Melaleuca oil and its constituents. Previous studies reported Melaleuca oils to exhibit anticancer activity in vitro against a range of cancer cell lines, including melanoma, liver, leukaemia, lung, breast, and prostate cancer. However, much still remains to be discovered and elucidated about the Melaleuca oils, TTO and MAC. This thesis investigated the hypothesis that MAC represented an effective anticancer agent with immunomodulatory activity.