Invasive fungal infections (IFI) continue to be an important cause of morbidity and mortality in patients with hematological malignancies. Candida and Aspergillus species constitute most of the IFI in these patients.. It has been reported that most of the invasive aspergillosis epidemics are related to the construction works in the hospital. In this study, we aimed to investigate the frequency of IFI in the old and the new hospital building after relocation in patients with hematological malignancies. Of 8042 patients who were hospitalized in the Department of Hematology, Ondokuz Mayıs University Faculty of Medicine between January 2015 and September 2019, 412 patients who were initiated antifungal therapy were included in the study. The patients in the hematology clinic, which were moved to the new oncology hospital building in January 2018, were grouped as prior and after relocation, and their demographical data, hematological diagnosis, chemotherapy regimens, mortality, IFI, focus of infection, presence of central venous catheter, antifungal prophylaxis and treatment, galactomannan level, fungal culture and computed tomography (CT) findings were evaluated retrospectively. It was determined that 55% of the patients were male and the median age was 58 (range:18-93). The rate of IFI development was 5.12% (n= 412) and the rate of invasive mold infection was 1.2% (n= 145). The most common hematological disease for which antifungal treatment initiated was acute myeloid leukemia (AML) with a rate of 50% (n= 206/412). Of patients, 73% received induction chemotherapy (42%, first induction, 31% reinduction), 13.4% received consolidation therapy. Invasive mold infection was diagnosed as 40% possible, 59% probable, 1% proven. While patients had similar characteristics such as age, gender, hematological disease, chemotherapy regimens and antifungal prophylaxis prior and after transportation, the rate of development of invasive mold infection was 2.1%, 2.06 / 1000 patient days, before transportation, 1.37% (p= 0.009), 1.15/1000 patient days (p< 0.001) after transportation, and it was statistically significantly lower after transportation. The median value of galactomannan antigen was detected as 0.17 (0.02-5.9). Blood cultures revealed 10.3% fungal growth and the most common growth was Candida albicans with 54.8% and Mucor spp. as mold with 3.2%. Large-scale construction works such as renovation, extension and demolition works in old hospital buildings are a permanent condition in different units. Clinicians should be aware of that infections due to opportunistic fungi can be seen in immunosuppressive patients close to such construction sites, and even cause epidemics. It should be kept in mind that these infections, which can progress with serious morbidity and mortality are difficult to treat but can be prevented by infection control measures.