The effects of long-term administration of fructose-added glycerol solution (Glyceol): 10% glycerol, 5% fructose, 0.9% sodium chloride; 600-2000 ml/d intravenously for 7-63 d) were evaluated in a multi-institutional trial involving 1346 cases. Improvement of the neurological signs and symptoms of elevated intracranial pressure was recognized by responsible physicians in close association with the administration of Glyceol (75.1%). The intracranial pressure measured directly also decreased in most cases following the administration of Glyceol (81.2%). No significant changes were observed in serum electrolytes and osmolarity at the end of the long-term administration. Unfavourable changes in clinical conditions which were considered very likely or suspected to be due to the long-term administration of Glyceol were recorded in 2 cases (0.1%) or 13 cases (1.0%), respectively. Most of these changes were abnormalities of serum electrolytes. It appeared, however, that the abnormalities of serum electrolytes may be readily correctable, and rarely induced if standard care of the serum water-electrolyte balance is carried out and unless too large doses are employed. Other changes appeared to be related more to preexistent complications and/or the administration of other drugs, rather than to the administration of Glyceol alone. Thus, administration of Glyceol appeared feasible for the therapy of elevated intracranial pressure over the long term.