Gamma-aminobutyric acid (GABA)-ergic transmission from the hypothalamus is essential for normal feeding regulation, and hyperphagia can be induced by local application of GABAA-receptor agonists to different feeding-associated brain areas. The food intake in rats varies diurnally and that may influence the effect of GABAA-receptor active compounds. The progesterone metabolite allopregnanolone is a highly potent endogenous positive modulator of the GABAA receptor. Therefore, it is easy to envisage that allopregnanolone would have a hyperphagic effect, but earlier reports in rat have given ambiguous results. However, a contributing factor for the discrepancy may be the time point of the diurnal cycle in which the experiments were performed. The aim of this study was to investigate the effect of allopregnanolone on intake of standard chow in male Wistar rats at different time points of the day.