Histoplasmosis is an endemic fungus in several regions of the United States. The diagnosis and treatment of this infection can be challenging in pediatric oncology patients. We present 5 patients diagnosed with histoplasmosis while receiving treatment at a midsize pediatric oncology center in Iowa. Two cases occurred in patients with acute lymphoblastic leukemia and 3 cases in patients with solid tumors. All patients were treated with antifungal therapy and demonstrated excellent clinical response. Histoplasmosis should be considered as a potential cause of nonspecific febrile illness, pulmonary masses, and bone marrow suppression in immunocompromised patients in endemic regions. Prompt and accurate diagnosis can facilitate timely antifungal therapy and avoidance of prolonged hospital stays, invasive testing, unnecessary antibiotics, and unwarranted anticancer therapies.