The aim of this systematic review was to assess the effectiveness of Chinese medicinal herbs used concurrently with cancer treatments in terms primarily of toxicity management but also quality of life and survival in adult cancer patients. Forty-nine trials met the inclusion criteria and were reviewed according to standard processes of systematic reviews. These trials included 3992 patients. All studies with the exception of one were of low methodological quality. The vast majority of the studies have shown that Chinese medicinal herbs improved treatment side effects, quality of life, and performance status, and some have provided evidence of tumour regression and increased survival. While no clinical recommendations can derive from such low quality studies, the number of studies reporting positive results is high enough to suggest that Chinese medicinal herbs may have a role in cancer care. However, more methodologically rigorous studies need to be developed as a priority before any firm conclusions can be drawn.