Penicillium marneffei (P. marneffei) is a pathogenic fungus that can cause fatal infections in humans, particularly immunocompromised hosts. It is prevalent only in the Southeast Asian region. A 5-year-old boy was presented with diagnosed Acute Lymphoblastic Leukemia undergoing chemotherapy and suffering from high-grade fever for 15 days positively responded to antibiotics on the initial day, but later he became unresponsive. He was found negative for blood cultures of bacterial growth. Ultrasound of the abdomen showed a borderline enlarged liver with multiple small hypoechoic areas of variable sizes seen scattered in both lobes of the liver. Morphological and microscopic analyses of liver tissues showed multiple septate hyphae of P. marneffei. Amphotericin B was found to be effective in treating the child. Appropriate identification is essential to treat the pathogen-causing disease, especially in immuno-compromised conditions like a leukemic patient, and determine underlying mechanisms behind the pathogenesis.