A prospective study of 70 patients admitted to the Rhode Island Hospital and treated for glutethimide intoxication conservatively, without hemodialysis, was undertaken. The diagnosis was confirmed in each case by elevated blood glutethimide levels; mixed intoxications with barbiturates were excluded by negative blood levels. Although only 1 patient died, 31 were unresponsive on admission and had complicated clinical courses associated with significant morbidity. Blood and cerebrospinal fluid glutethimide levels obtained on admission and subsequently were poorly correlated with duration of coma or morbidity. We conclude that (1) plasma glutethimide values are needed to confirm the diagnosis but are of little prognostic significance; (2) conservative treatment is associated with a very low mortality, although frequent and significant morbidity does occur among comatose patients; and (3) hemodialysis would appear to be needed rarely in the treatment of patients with glutethimide intoxication.