Invasive fungal infections are a serious complication for haematology patients. However, there is no study on this subject in Reunion Island. The aim of this study was to estimate the incidence of invasive fungal infections in patients with haematological malignancies at the University Hospital of Reunion Island. We conducted a descriptive and ambispective study. We included any patient with haematological malignancy presenting with a putative, possible, probable, or proven invasive fungal infection, defined as per the criteria of the European Organisation for Research and Treatment of Cancer/Mycoses Study Group 2019, from January 2018 to December 2022. Data were collected from medical records and identified by ICD-10 coding and laboratory data. Eighty-nine invasive fungal infections were diagnosed in 76 patients. The 5-year incidence rate of invasive fungal infections was 1.7 per 100 person-years (95% Confidence Interval (CI) 1.3-2). Invasive aspergillosis was the most common infection (35/89, 39%), followed by invasive candidiasis (33/89, 37%), mucormycosis (7/89, 8%), and pneumocystosis (7/89, 8%). Most infections occurred in patients with acute myeloid leukaemia (32/89, 36%) and lymphoma (26/89, 29%). Six-month mortality was higher for mucormycosis (71%) than for aspergillosis (34%) and invasive candidiasis (33%). The incidence and distribution of fungal infections in haematology patients were similar to European cohorts, albeit with more mucormycosis, less pneumocystis, and a high proportion of Candida parapsilosis in candidemia.