In the ventricles of the brain there is a structure called the choroid plexus where cerebrospinal fluid is produced. Recent research has shown that its role is much broader. It also acts as a barrier for the transfer of substances between the blood and the brain, is involved in the active transport of important substances to the brain, in protecting the brain from neuroinflammation and in the removal of metabolic products of the brain, including those that cause neurodegenerative diseases such as Alzheimer's disease and others. Previous studies have shown that the choroid plexus has a robust circadian clock that controls many of its functions to vary throughout the day and night. In our study, we monitored the clock in the choroid plexus in real time under ex vivo conditions by recording rhythmic changes in bioluminescence that correspond to changes in levels of one of the proteins (PER2) essential for the molecular operation of the clock. We found that disrupting the daily regime in the mouse by altering the light-dark cycle (chronodisruption) not only disrupts the clock in the suprachiasmatic nuclei that controls the sleep-wake cycle, but also significantly suppresses the rhythm of the clock in the choroid plexus. A surprising finding was that, unlike other clocks in the body, the clock in the choroid plexus was completely resistant to the pro-inflammatory state induced by the chronodisruption or by the application of lipopolysaccharide. The mechanism of this resistance is likely related to the specific response of the choroid plexus to chronodisruption at the level of glucocorticoid signaling. The results show high sensitivity of the clock in the choroid plexus to disruption of the circadian system. In addition, they showed that operation of the clock is preserved even during proinflammatory state. These results form the basis for a new direction of research into the impact of disrupted function of the clock in choroid plexus on brain homeostasis.