Pharmacological fMRI (phfMRI) is widely utilized to study the effect of specific drugs on brain circuitries and neurotransmitter systems. Some drugs induce elevations in mean arterial blood pressure (MABP) which can increase cerebral blood flow (CBF) and translate into blood oxygenation level-dependent (BOLD) effects. Dynamic autoregulation buffers abrupt changes in MABP to keep CBF relatively constant in a particular range, which was previously defined in rats as 60-120 mmHg and sanguinely applied to mice. By pharmacologically challenging and monitoring the MABP during fMRI we show that these limits of dynamic autoregulation do not apply to mice. Therefore murine phfMRI studies should be interpreted with caution.