Introduction: Ulcerative colitis (UC) is an inflammatory bowel disease (IBD), in which the role of pro-inflammatory cytokines and oxidative stress in its underlying pathogenesis has come into focus. Pistacia Atlantica (P. atlantica) is used in traditional Persian medicine for the management of gastrointestinal disorders. Hence, the present study aimed to investigate the protective effects of hydroalcoholic extract of P. atlantica leaves on acetic acid-induced UC in a rat model. Methods: Male Sprague-Dawley rats were assigned to six groups: normal, colitis by transrectal administration of 4% acetic acid, colitis + sulfasalazine (sulfa, 500 mg/kg/day, intraperitoneally (i.p.)), and colitis + P. atlantica leaves hydroalcoholic extract (at 50, 100, 200 mg/kg/day doses). P. atlantica was administered via oral gavage for 3 consecutive days. After 7 days, colons were resected for macroscopic damage score and histopathological assessment. Furthermore, antioxidant status and inflammatory markers were measured in the serum. Results: Macroscopic and histopathological analysis of the mucosa showed that P. atlantica significantly alleviated colonic damage in a concentration-dependent manner (P<0.001 to P< 0.01). Importantly, in the group treated with P. atlantica, there was a significant reduction in serum nitric oxide (NO) levels (P<0.001), along with restoration of antioxidant systems, as indicated by increased superoxide dismutase (SOD) activity and glutathione (GSH) levels, compared to the colitis rats (P<0.001). Conclusion: These findings indicate the therapeutic potential of P. atlantica leaves in alleviating the severity of colitis in rats by suppressing inflammation and oxidative states in the serum, which could be used as an appropriate drug for the management of UC.