Mucormycosis is a disease caused by opportunistic fungi of the order Mucorales that generally affects immunocompromised patients or those with underlying disease. It has a high mortality rate and is the third most common invasive fungal infection. The following is a case report of a 12-year-old pediatric patient diagnosed with B-cell acute lymphoblastic leukemia, who presented an aggressive infectious disease two months after beginning chemotherapy, which began in the right frontal and maxillary sinuses, with subsequent progression and extension, progressively SUMMARY deteriorating the patient's clinical status. Culture and biopsy of the affected areas were performed, confirming by histopathology and isolation a rhino-orbito-cerebral mucormycosis due to Actinomucor elegans. The patient was treated with specific antifungal therapy as an inpatient and left the service after obtaining negative cultures, continuing with outpatient antifungal treatment.