Medical tourism has grown globally, especially in oncology field, but it may cause serious problems. We aimed to elucidate concerns generated by medical tourism at a Japanese hospital and recommend solutions.We evaluated 72 consecutive patients with cancer who had traveled from abroad to receive second opinions, clinical examinations or treatments at our hospital between January 2015 and December 2016. Data were retrospectively collected to include the purpose of patients' visits, presence and content of referral documents, details of treatments provided at our hospital, concordance between treatments received and patients' expectations, troublesome hospital incidents, risks of travel and problems with payment.The purpose of the visit was actual cancer treatment in the majority of the cases. Thirteen patients could speak neither Japanese nor English. Inadequate content in patient referral documents and discordance between information from the referring physician and findings at first examination were the main issues observed in the pre-treatment phase; 33 patients decided to receive treatment at our hospital. Language differences caused problems in patients' understanding of instructions and explanations during treatment. Additional problems included inaccurate self-evaluation of disease status, differences in cultural habits and requests for inappropriate and/or unavailable therapies. No major issues that could lead to injury in patients or medical staff were observed. Risks involved with returning home and transfer of treatment to local physicians were the main post-treatment issues.Medical tourism raises various issues. Institutional and medical staff should be adequately prepared by developing working systems.