The number of children and young people diagnosed with cancer is increasing every year. Pain is a significant side effect of disease, surgery and treatments including chemotherapy. After a course of intensive chemotherapy, some children develop oral mucositis, a debilitating condition causing bleeding, pain and inflammation. Moderate and severe mucositis pain is treated with continued good oral hygiene and parenteral analgesia. The aim of this article is to identify challenges in managing chemotherapy-induced oral mucositis pain in children, and to highlight the benefits of adding ketamine as an adjuvant analgesic. A small number of studies and case reports in children have examined ketamine for cancer pain and have demonstrated its successful use in the treatment of chronic pain conditions. However, there remtains a paucity of data about the efficacy of continuous low dose ketamine administration in children with cancer. Further studies are required to establish its benefits to support the addition of ketamine to the World Health Organization’s analgesic ladder.