Aims: The gastrointestinal tract exhibits circadian rhythms in many physiological functions. The aim of the present study was to find out whether restricted feeding (RF) regime may synchronize disturbed circadian clocks within the rat liver and gut. Methods: The control groups of animals were kept under the regimes with 12 h of light and 12 h of darkness (LD 12:12) or under constant light conditions (LL) and fed ad libitum. The experimental groups were maintained under LD 12:12 or LL, but access to food was restricted to only 6 h during the resting time (RF). Locomotor activity was recorded during the whole experiment. Daily expression profiles of clock genes Per1, Per2, Bmal1 and Rev-erb-a were examined by real-time RT-PCR. Results: Under LD conditions, the locomotor activity and clock gene expression profiles in the liver and gut exhibited significant circadian rhythmicity in rats fed ad libitum; the RF regime phase-advanced the expression geneprofiles similarly in both tissues. Under LL conditions, the locomotor activity and clock gene expression profiles in the liver and gut were arrhythmic in animals fed ad libitum and the RF regime affected the daily gene expression profiles differently in the individual tissues. In the liver, Per1, Bmal1 and Rev-erb-a genes were expressed rhythmically and a rythm in Per2 expression was suggested. In the gut, Rev-erb-a and Bmal1 were expressed rhythmically, while expression of Per1 and Per2 did not exhibit circadian rhythmicity. Conclusions: Under conditions of disturbed circadian system via exposure to LL, the RF regime restored rhythms in clock gene expression profiles in theliver and gutwith different efficiency due to competition between the signaling from the circadian system and food. Our data suggest that regular food intake mayrepresent efficient cue to synchronize the gastrointestinal rhythmicity even under conditions when circadian system is disrupted by external lighting conditions.