Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease due to infection with polyomavirus JC (JCV). PML occurs almost exclusively in immunocompromised patients, and although it has increased markedly in relation to AIDS, remains exceptional in children. We present the case of an immunocompromised child with hyperimmunoglobulin E recurrent infection syndrome (HIES) and pathologically-proven PML. HIES is a rare congenital immunodeficiency that to our knowledge has never before been reported in association with neurological complications. Following a recurrence of bronchopneumonia, the child's motor and cognitive functions deteriorated progressively in parallel with alterations on cerebral MRI. The neurological onset coincided with lymphocyte subset changes. PCR for JCV DNA did not detect the virus in CSF, and brain biopsy was required to secure the diagnosis. Antiviral treatment with cidofovir produced no benefit. Autopsy revealed the typical neuropathological findings of PML which were associated with inflammatory eosinophilic infiltrate (a marker of HIES). In accordance with the few pediatric PML cases reported and here reviewed, the child died five months after neurological onset.