Long survival in subacute sclerosing panencephalitis (SSPE), including total disappearance of clinical signs, is rare. Two cases are reported. They concern a girl and a boy who, at age 13 and 15, developed SSPE and are still in remission 6 and 5 years later. After a typical onset and course over periods of 12 and 18 months, clinical improvement was observed and periodic EEG complexes disappeared. However, the electrophoretic oligoclonal pattern of CSF proteins and the elevated measles titers persisted (in one case specific CSF IgM were still increased 6 years after the onset). MRI showed asymmetrical areas of high-intensity signal in both white and gray matter, predominant in the temporal, parietal and occipital regions. The age at which SSPE begins and the interval between measles and SSPE onset are not prognostic factors. On the other hand, in reported cases with lasting remission SSPE did not progress beyond Jabbour's stage II. The second typical feature of these long-term improvements is disappearance of EEG periodic complexes and emergence of a normal basic background activity. No other prognostic factor has been reported.