Introduction: Protothecosis, a rare fungal infection caused by Prototheca species, is generally introduced via traumatic inoculation and mostly displays three clinical forms; cutaneous, olecranon bursitis, and systemic infection. Only a few cases of protothecal meningitis have been documented. We present a rare case of Prototheca wickerhamii meningitis in a child complicating with hydrocephalus and cerebral infarction. Case report: A previously healthy 12-year-old boy was admitted due to gait disturbance for a month without antecedent febrile illnesses, headache or dizziness. Neurologic examination revealed bilaterally decreased visual acuity, sluggish right pupillary light reflex in both direct and indirect tests, and dystonia and uncoordinated movement in the right lower extremities. Bilateral optic edema and peripapillary retinitis was identified by an ophthalmoscopic examination. Brain magnetic resonance imaging demonstrated communicating hydrocephalus and irregular T2 hyperintense lesions in the left internal capsule and bilateral thalamus suggesting old infarction. A ventriculoperitoneal (VP) shunt was inserted and revealed 430 mmH2O of opening cerebrospinal fluid (CSF) pressure. CSF analysis showed; white blood cells 150/μL (68% eosinophils, 27% lymphocytes), protein 71.8 mg/dL, and glucose 35 mg/dL. Whereas other CSF cultures for viral and bacterial infections were negative, fungus culture proved Prototheca wickerhamii meningitis. Thorough immunologic examination and screening for systemic infection were normal findings. Following the administration of intravenous amphotericin B, CSF fungus culture was converted to negative at 4 weeks after treatment and CSF cytology was normalized at 7 weeks after treatment and he showed marked improvements of motor deficits. VP shunt was removed after 9 weeks of treatment and amphotericin B was continued for 12 weeks. Despite mild hydrocephalus on the following head computed tomography and visual defect caused by optic neuritis remained, he is now free of headache and motor deficits. Conclusion: We describe a rare case with protothecal meningitis presenting as hydrocephalus and cerebral infarction in an immunocompetent child, who was successfully treated with ventricular decompression and antifungal therapy. In a patient with subacute onset of hydrocephalus, atypical infection should be considered.