Introduction: Aspergillus exhibits a wide variation of susceptibility against antifungals according to genetic and environmental factors. Identification to the species level is necessary for appropriate treatment. Our objective was to determine the Aspergillus species involved in invasive pulmonary aspergillosis (IPA) among ICU patients in Jakarta, Indonesia. Methodology: The incidence of IPA in ICU patients at six hospitals in Jakarta from October 2012 - January 2015 was investigated. It involved a collection of endotracheal aspirates (ETA), nasal swabs and environmental samples around the hospitals, phenotypic screening, molecular characterization, and antifungal susceptibility testing. Results: Of the 405 patients investigated, 31 patients (7.7%) were diagnosed with putative IPA, from whom 45 Aspergillus isolates were collected. Aspergillus isolates were identified from pulmonary secretions in 24 patients, from nasal swabs in 7 patients and from both pulmonary secretions and nasal swabs in 7 patients. The phenotypic method showed 33 isolates of Aspergillus flavus (73.4%), nine Aspergillus fumigatus (20%), two Aspergillus niger (4.4%), and one Aspergillus nidulans (2.2%) isolate. Molecular identification showed 27 isolates of A. flavus (60.0%), eight isolates of A. fumigatus (17.8%), two isolates of A. niger (4.4%) and one isolate of A. nidulans (2.2%), while seven isolates (15.6%) were cryptic species or mixed isolates. Conclusions: Susceptibility testing showed all isolates were susceptible to amphotericin B, azoles and micafungin. Aspergillus flavus was the main causative organism in IPA cases in Jakarta, followed by A. fumigatus. © 2021 Journal of Infection in Developing Countries. All rights reserved.