The effects of halothane or isoflurane, alone and in combination with propofol or thiopental were investigated for their effects on intracranial pressure (ICP) in the rabbit, with inducing artificially-increased ICP with an intracranial balloon. The higher the end-tidal concentrations of either halothane or isoflurane, the lower the mean arterial pressures (MAP) and cerebral perfusion pressures (CPP). However, the ICP was not influenced by the depth of anesthesia for either inhalation anesthetics. The mean ICPs at 1.5 MAC of halothane and isoflurane were 14 ± 2 and 20 ± 2 mmHg, respectively. With the increase of intracranial volume using a 0.7 ml-saline balloon, the ICPs were increased to 193 and 205% in halothane and isoflurane anesthesia, respectively. The ICPs were returned to the levels prior to balloon inflation by the injection of thiopental or propofol. The authors conclude that propofol could be used to reduce ICP under halothane or isoflurane anesthesia if it is ascertained to have the characteristics of a balanced coupling between cerebral metabolism and blood flow like barbiturates do and that either halothane or isoflurane with increased concentrations may decrease MAP without significant change of ICP.