In preclinical fMRI, the volatile anaesthetic isoflurane is valued for its ease of use and controllability, and is frequently applied to prevent anxiety and subject motion. Yet, isoflurane increases cerebral blood flow and particularly in mice it limits cerebrovascular response to neural activity, thus curtailing fMRI. Sevoflurane, a close relative to isoflurane, has been reported to be less vasodilatory. Hence, we evaluated whether sevoflurane could serve as an improved anaesthesia modality for fMRI in mice. Perfusion MRI however revealed high basal cerebral perfusion and restricted cerebrovascular reserve capacity in an acetazolamide-induced hypercapnic challenge akin to those previously reported for isoflurane.