This study investigated the effect of adding extracts from selected herbs to water on alleviation of broiler stress associated with intensive production, and thus on improvement of welfare. In experimental groups (II, III and IV), alcoholic extracts from chamomile inflorescence (Matricaria
chamomilla L.), lemon balm (Melissa officinalis L.) or from St John’s wort (Hypericum perforatum L.), respectively, were added to water drinkers (2 ml ∙ l-1 water) from 21 to 35 days of rearing for 5 h/day. Throughout the experiment, body weight, feed and water intake and number of dead birds were recorded once a week. At 21, 28, 35 and 42 days of rearing, blood was collected from 7 birds in each group to determine the levels of corticosterone, cholesterol, glucose, and the immunoglobulin complex. The response of birds to the herbal additives was positive. The herb extracts contributed to a decrease in cholesterol level and an increase in the level of the immunoglobulin complex in the blood. Supplementation of water with chamomile and St John’s wort extracts contributed to an increase in body weight, while the extracts from lemon balm and St John’s wort also had a positive effect on broiler survival. The results obtained indicate that out of the three herbs chosen for the experiment, St John’s wort extract proved the most efficient in relieving the body’s physiological response to stress, and thus in improving welfare.