This report describes a man aged 65 years who developed spastic paraparesis secondary to arachnoiditis ossificans in the thoracic spine. Over 35 years previously, in Southeast Asia, the patient had received repeated lumbar punctures in the treatment of meningitis possibly associated with malarial fever. He had multiple arachnoidal ossifications located at levels from T6 to T9 dorsal to the spinal cord which were well delineated by computed tomography. The lesions were completely extirpated by dorsal route surgery, and the patient had marked neurological improvement after surgery. Histology confirmed that the lesions showed mature bone that formed with an osseous marrow and trabeculae, and the lesions exhibited clusters of arachnoidal cells as well as the proliferation of osteoblasts surrounding the ossified area. Early diagnosis and surgical intervention, however, are mandatory in such cases, if the patient is to attain an acceptable degree of recovery.