Background: Mucormycosis is the third most common invasive fungal infection in children and primarily affects immunocompromised patients with cancer. Incidence rates and contemporary survival statistics are needed in view of current cancer management protocols, availability of molecular tests and newer antifungals. Methods: A retrospective chart review of cases of mucormycosis in patients with oncologic diagnoses at the Children’s Hospital of Eastern Ontario, in Ottawa, Canada, between 2000 and 2020 was completed. We describe the clinical characteristics, diagnosis, treatment, and outcomes and inform areas for future research. Results: Over 20 years, the incidence rate among hematology-oncology patients was 0.66% with four cases identified. The underlying diagnosis in these cases was ALL(n=3) and AML(n=1). The average age at diagnosis of mucormycosis was 7 years. The sites of infection were cutaneous (perianal), disseminated, rhino-orbito-cerebral and pulmonary. All patients were receiving induction chemotherapy at the time of infection. Most were on high-dose steroids(n=3) and antibiotics(n=3), and half(n=2) were on antifungal prophylaxis. Mucormycosis was diagnosed using histopathological, culture and/or PCR results. Rhizopus species was most commonly isolated. ABLC was the mainstay of treatment, but all patients received combination antifungal therapy. Two patients underwent surgical debridement/resection. All cases had delays in their cancer treatment secondary to infection. Mucormycosis-related mortality was 25 percent. Conclusions: Mucormycosis has a high morbidity and mortality affecting immunosuppressed individuals. Given its rarity and heterogeneity in clinical presentation, diagnosis is often delayed. This case series shows that with early diagnosis, aggressive anti-fungal therapy with possible adjunctive surgical intervention, positive patient outcomes can be achieved.