Tissue oxygen tension in the stria vascularis was successfully measured in cats using the polarographic technique. A correlation study using the differential coefficient between oxygen tension in the stria vascularis and systemic blood pressure proved that vascular autoregulation is present in the mean systemic blood pressure range between 40 and 80 mmHg. The anatomical findings and the response patterns to different gas inhalations indicated that the type of vascular regulation present is more closely related to chemical control than to auto-regulation.