The objectives were to review the existing literature on management of opioid-induced nausea and vomiting in cancer patients and summarize the findings into evidence-based recommendations. Systematic searches of MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were performed, using free text and MeSH/EMTREE search terms. The searches were limited to articles published in English from each database set-up date to 31 July 2009. Reference lists and relevant international conference proceedings were hand-searched. Fifty-five studies were identified, providing data on 5741 patients. The studies were classified into: (A) studies in which treatment of nausea/vomiting was the primary outcome (a total of 18 studies, of which eight studies specifically addressed opioid-induced emesis); and (B) studies in which nausea/vomiting were secondary or tertiary outcomes (37 studies). The existing evidence had several limitations, there was a lack of consistency and the overall quality was grade D. By applying the principles of the Grading of Recommendations Assessment, Development and Evaluations (GRADE) system, three weak recommendations were formulated. The current evidence is too limited to give evidence-based recommendations for the use of antiemetics for opioid-induced nausea or vomiting in cancer patients. The evidence suggests that nausea and vomiting in cancer patients receiving an opioid might be reduced by changing the opioid or opioid administration route. The evidence was also too limited to prioritize between symptomatic treatment and adjustment of the opioid treatment.