Curvularia species are saprophytic dematiaceous fungi commonly isolated from environmental sources. Most often, they are responsible for allergic fungal rhinosinusitis, an intense, allergic inflammatory sinus disease in immunocompetent individuals. Though invasive infections are rare and more commonly observed in immunocompromised patients, recent reports indicate an increasing trend of invasive sinusitis caused by Curvularia species in immunocompetent hosts. Over the past few years, new species of the genus Curvularia are increasingly being recognized as human pathogens. Here, we report the first human infection caused by Curvularia warraberensis, a cryptic species of Curvularia primarily described as an endophyte in Australian grasses. The 33-year-old female presented with chronic invasive sinusitis of the sphenoid and ethmoid sinuses that progressed to involve the pituitary gland, mid-brain, the facial-vestibulocochlear nerve complex, and basilar artery. The patient underwent endoscopic sinus surgery. Histopathology, microscopic examination and culture of biopsy tissues revealed a dematiaceous fungus that was identified as C. warraberensis, based on sequencing the internal transcribed spacer (ITS) and large subunit (LSU) regions of ribosomal DNA. Antifungal susceptibility testing (AFST) showed low minimum inhibitory concentrations (MICs) for amphotericin B (1 µg/mL), itraconazole (0.25 µg/mL) and posaconazole (0.125 µg/mL). Accurate identification and AFST are crucial for making treatment decisions as some Curvularia species demonstrate variable susceptibility to antifungal agents. The patient died despite combined surgical and medical intervention owing to late presentation and delay in initiating antifungal therapy. A high index of suspicion together with an early diagnosis and aggressive treatment may improve the outcome in such cases.