Giant cell tumors (GCTs) are rare bone tumors that account for similar to 5% of all primary bone tumors. When GCTs occur in the spine, patients usually present with localized pain and neurological symptoms, such as radiating pain or hyperesthesia. In the current report, an unusual case of a GCT of the thoracic spine associated with hydrocephalus is described. A 48-year-old male presented with urinary retention, loss of sensation in the lower limbs and inability to walk. The patient eventually developed hydrocephalus combined with altered consciousness, indicated by an inability to follow simple commands. Magnetic resonance (MR) imaging demonstrated the presence of a soft tissue mass at the T2 level, and biopsy examination of the tissue confirmed that it was a GCT. The patient experienced a sudden loss of consciousness due to an acute episode of obstructive hydrocephalus. A ventriculoperitoneal shunting procedure was performed to treat the hydrocephalus, and the patient regained normal consciousness, although the paraplegia persisted. An MR examination performed 30 months following surgery demonstrated that the tumor size was stable, consistent with the slow growth that is characteristic of GCTs. Diagnosis of GCTs may be challenging, and relies on radiographic and histopathologic findings. Although rare, acute hydrocephalus as a result of GCTs should not be excluded from a differential diagnosis.