OBJECTIVES: This study investigated the impact of drinking hydrogen-rich water (HRW) on growth performance, organ weights, thiol/disulphide homeostasis, oxidative status and some hormonal, histopathological and immunohistochemical changes in rats fed in a restricted housing environment. METHODS: The eight groups (each group [male/female] eight rats) comprised two control, two hydrogen, two stress and two stress + hydrogen. All animals were given feed and water ad libitum for 3 months. Control and HRW group rats were calculated according to weight and housed according to the Guide's housing condition. The stress group and stress + HRW group were housed in half the area of the Guide's housing condition according to their weight. The animal's weekly body weights were measured throughout the study. The animals were sacrificed in accordance with ethical rules. Then, biochemical analyses were performed on thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), cortisol, parathyroid hormone (PTH) and calcium (Ca RESULTS: Results showed that live weight gain was higher in the HRW groups than in the stress group. Oxidant status in biochemical analyses decreased in the stress + HRW group compared to the stress group. TSH decreased in the stress group. FT4, cortisol and Ca CONCLUSIONS: The stress-related physiological parameters were reduced in the HRW + stress group compared to the stress group. HRW could be suggested when the organism is found in stressful conditions.