We treated three patients with subacute sclerosing panencephalitis with intraventricular interferon-α and oral inosiplex, and followed their clinical courses. One patient was also treated with ribavirin. Results were unsatisfactory; no significant clinical improvement was seen in the patients, and a number of serious complications occurred. Malfunction of the Ommaya reservoir, septic meningitis and chemical encephalopathy were observed in the three patients, respectively. The use of intraventricular interferon-α and ribavirin therapy has been increasing despite insufficient evidence of its efficacy. A high risk of serious side effects exists with this therapy. Thus it is important to consider not only the effects but also the side effects and complications as described above. We also propose that a standard protocol for the use of interferon-α and ribavirin and the cessation of current therapy is necessary.