The aim of this study was to determinate the effect of high barn temperature on animal behaviour in Holstein dairy cows. The experiment was conducted on University's farm in Zabcice from 27th June to 27th July 2017 at an average outside air temperature of 25.9 degrees C and 25.5 degrees C temperature inside the barn. Two groups of dairy cows (72 animals each group) were included in the experiment. Dairy cows were housed in free stall bedded barn. Ethological manifestations (presence of dairy cows inside the stall lying down or standing, presence of dairy cows outside the stall in corridor or in feeding area) were recorded for each group three times a day (in the morning, at the noon, before leaving for the parlor), two consecutive days a week. The bioclimatic parameters were measured concurrently outside and inside the barn (in the living area of both groups). Monitored dairy cows were fed during the entire monitoring period identical TMR. Results of our study demonstrated the effect of high barn temperature on dairy cows behaviour. Overall, dairy Cons were standing more than lying down, by 4%. However, while sections 1 and 9 did not have a more significant impact on ethological manifestations of dairy cows (dairy cows in both section acted the same way they were lying down more than standing, except for slight variations), we found out significant differences in dairy cows behaviour in assessing the preferences of the individual rows of stalls. The highest number of dairy cows were in the middle row (B) compared to the row A (row closer to the feeding area) and the row C (row at the perimeter wall). Nevertheless, the proportion of individual dairy cow ethological manifestations in the individual rows (A, B, C) Was comparable.