Fever in people with cancer needs rapid evaluation because, if associated with neutropenia, may be life-threatening and necessitates urgent treatment. Oral or axillary temperature measurement is recommended rather than rectal or oral because of the risk of translocation of bacterial infection due to insertion of the probe into the rectum. Fever is common in the cancer population with 10% to 50% of patients with a solid tumors and more than 80% of those with a hematologic cancer treated with one or more chemotherapy cycles. The use of immune-checkpoint inhibitors has also been implicated in the development of febrile neutropenia. Oral mucositis is an additional contributing factor; assessment of the mouth including salivary glands is important to identify the source of infection leading to fever. Primary prevention in those at risk of neutropenia involves prophylactic antimicrobials. Similarly, antimicrobials should be prescribed to prevent recurrent infections.