Kisspeptin, the regulatory peptide, is known as a fertility stimulator and reproductive regulator. Its activity is mediated by specific interaction with GPR54 receptors (or Kiss1R). There are indications of correlation between the kisspeptin system in the brain and the function of circadian oscillator, the suprachiasmatic hypothalamus nucleus, which stimulates the cells of the kisspeptin neural network of the anteroventral periventricular nucleus in the hypothalamus, which in turn leads to the release of the hypothalamic gonadoliberin in the time period immediately preceding the start of the total daily locomotor activity. There is also evidence on the presence of fibers containing kisspeptin and on kisspeptin receptor expression in the suprachiasmatic nucleus, which indicates the function of kisspeptin as a feedback signal from the reproductive to the circadian system. Along with kisspeptin reproductive function, there is evidence on its importance in the behavior regulation. The aim of the work is to study the effect of intranasal administration of a specific GPR54 antagonist of p-234 receptors on the behavior of male rats in standard tests, such as “Open Field” and “Dark-Light box”. Materials and Methods. The experiments were conducted on 12 Wistar male rats weighing between 240 and 270 g. For control and experimental groups, the 12:12 h. light/dark illumination mode was set. The studies were conducted in the first half of the circadian day. In the experimental group the antagonist of p-234 kisspeptin receptors was administered intranasally; in the control group water for injection was administered using the same method. Results. Administration of kisspeptin receptor antagonist to experimental animals at the beginning of the subjective day led to a decreased anxiety level and stimulated the exploratory behavior in rats. Conclusion. The revealed behavioral changes can contribute to the implementation of the already known kisspeptin function as a reproductive stimulator, or act as an independent component in the physiological activity of a kisspeptin system. Keywords: antagonist of kisseptin receptors p-234, behavioral tests.