We examined the effects of the recently developed calcium antagonist HA1077 on cerebral haemodynamics during the chronic stage of the two-haemorrhage canine model system of vasospasm. Regional cerebral blood flow (rCBF), regional cerebral blood velocity and regional cerebral blood volume in the canine parietal cortex were measured by Laser-doppler flowmeter. On the 7th day after the initial injection of autogenous blood, subarachnoid haemorrhage (SAH) produced a significant decrease in rCBF (59% of control, p less than 0.05) and blood velocity (48% of control, p less than 0.05) with no remarkable change in blood volume (108% of control). Bolus intravenous administration of HA1077 (0.1-0.3 mg/kg) dose-dependently increased the rCBF and blood velocity, without significantly changing the blood volume on Day 7 after SAH. HA1077 improves haemodynamic function manifested by an increase in rCBF and velocity in this SAH model, and may be suitable for the treatment of vasospasm in patients with SAH.