The objectives of this study were to evaluate the correlations between preoperative SjVO2 and prognostic factors (Glasgow coma scale, arterial blood pressure, PaCO2, glucose and blood lactate) in patients with severe head injury. A descriptive and prospective study was conducted with 50 head injuried patients undergoing craniotomy surgeries. Preoperative SjVO2 in jugular bulb was measured by a catheter connecting to a CeVOX monitor. Glasgow coma !)core (GCS), arterial blood pressure (ASP), PaCO2, glucose, and blood lactate were identified on admission to the operating theatre. The results showed that SjVO2 was in the normal range in 52 percent of patients, reduced in 32 percent and increased in 16 percent of patients. SjVO2 correlated strongly with PaCO2 and blood lactate (r = 0.6 and -0.6, p 0.01), moderatly with GCS and blood glucose (r