The histories of two patients with arachnoiditis ossificans leading to severe neurological impairment are presented. Analysis of these cases highlights the importance of three-dimensional (3 D) computed tomography (CT) scanning for the establishment of the diagnosis and in postoperative assessment of this rare disease, whereas magnetic resonance imaging (MRI) is less useful. The neurological function in both cases improved following re-exploration operations in which the whole length of the dural sac covering the intradural ossific lesions was freed totally from external obstructions imposed by the covering laminae.