This prospective, observational, multicenter study evaluated the real-world incidence of invasive fungal infection (IFI) during and after micafungin prophylaxis in France. Patients with a hematological malignancy/solid tumor received micafungin prophylaxis according to usual clinical practice and were followed for 3 months. Primary endpoint was breakthrough IFI incidence during prophylaxis. Secondary endpoints included the identification of IFI risk factors, IFI incidence during follow-up, and adverse events (AEs). One hundred and fifty patients (55 children, 95 adults) were enrolled. Micafungin prophylaxis was initiated at 50 mg in adults and at a median 1.01 mg/kg (range: 0.6-2.2) in children. Fifteen patients (10%) experienced an IFI during prophylaxis. IFI breakthrough occurred in 15% children, 7% adults, 3.1% allogeneic transplant patients, 8.7% acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS) patients, 7.0% other patients (never allotransplanted/non-AML/MDS). Nineteen patients (12.7%) experienced an IFI during 3-month follow-up. Micafungin was well tolerated with few treatment-related AEs, supporting its use in this patient population in France.