The study was performed to evaluate radiotherapy for patients with intramedullary spinal cord metastasis (ISCM) and to identify the clinical features of ISCM. The subjects were 18 patients (8 men, 10 women) with ISCM who underwent radiotherapy between September 2002 and February 2008. The primary lesions were lung cancer in 8 patients (2 small cell, 6 non-small cell), breast cancer in 6, malignant melanoma in 2, renal cell carcinoma in 1, and rectal cancer in 1 patient. Diagnosis, symptoms and survival of these patients were compared with those for 544 patients with vertebral metastases who underwent radiotherapy at the same institute between September 2002 and November 2006. In the 18 patients with ISCM, the 6-month survival rate after radiotherapy was 36% and the median survival period was 4.0 months. Ten patients had neurological improvement or pain relief after radiotherapy. Brain metastases were six fold more frequent in the patients with ISCM than in those with vertebral metastasis [89% vs. 15%, p = 0.001]. At the time of radiotherapy, back pain in patients with vertebral metastasis was more frequent [97% vs. 33%, p = 0.001] but neurological deficits were less common [24% vs. 100% , p = 0.001]. Most ISCM cases were diagnosed by contrast-enhanced MRI, with detection by contrast-enhanced CT in only 3/18 cases (17%). ISCM has a poor prognosis and most patients have neurological deficits that impair quality of life. Early diagnosis by MRI is important for suspected ISCM to allow initiation of radiotherapy before development of neurological deficits.