Two groups of 40 homogeneous patients (ASA physical status (1-2)) with idiopathic scoliosis undergoing spinal fusion with CD instrumentation were studied prospectively. Group A (intrathecal) received a mixture of morphine and sufentanil administered intrathecally at the level of L3-L4 after the induction of anaesthesia. Group B (control) had inhalation and intravenous narcotic anaesthesia. The use of intrathecal opioids resulted in a significant reduction of blood pressure without the use of any hypotensive agents and produced prolonged postoperative analgesia. There was no adverse effect on somatosensory evoked potentials. The dose requirement for the anaesthetic agents was significantly reduced and the blood loss was 27% of their blood volume compared with 53% in the control group. No long or short term impairment of cerebral or spinal function was observed. The use of intrathecal opioids supplemented with other anaesthetic agents is an alternative method with multiple benefits for any major surgery such as spinal fusion.