Background: Trichosporon asahii is an opportunistic fungus that causes infections in immunosuppressed patients. It is rarely seen in children and immunocompetent hosts. The mortality rates are still high despite early treatment with proper antifungal drugs. Trichosporon asahii mastoiditis in an immunocompetent child makes this case challenging. Case presentation: This report presents a case of Trichosporon asahii mastoiditis which was complicated by transverse sinus thrombosis, in an otherwise healthy 21-month-old girl, and successfully treated with voriconazole. Trichosporon asahii was isolated, in three different occasions, from ear discharge of an immunocompetent healthy child, who presented with prolonged history of fever and received appropriate dosages of multiple types of antimicrobials as an outpatient but without improvement. After 48 h of starting the Voriconzole; post auricular swelling and ear discharge improved significantly. Conclusion: A high index of clinical and microbiological suspicion is needed for optimal diagnosis of Trichosporon infection. Trichosporon asahii can also cause infection in immunocompetent individual even without previous history of hospitalization or intervention. We emphasize the importance of early pediatric infectious evaluation and intervention.