Backround and Aim: Autism is a clinically well-defined disorder that has no treatment yet. Other than behavior modification studies, medical treatments are still investigating. Rat is among the most frequently used experimental animals in such studies. Although various drugs cause autism in this animal species, propionic acid (PPA) was used in this study. Bismuth subsalicylate is frequently used in the treatment of gastrointestinal diseases in clinics and has anti-inflammatory and antacid effects. In our study, we examined the effects of bismuth in rats with autism using PPA. Materials and Methods: Thirty male rats were used in this study and 20 of them were given PPA intraperitoneally at 250 mg/kg/day for five days. Rats were randomly divided into three groups: Group 1 (no procedure was applied, n=10), Group 2 (intraperitoneal PPA+1 ml/kg/day % 0.9 salines given orally, n=10), and Group 3 (intraperitoneal PPA+60 mg/kg/day bismuth subsalicylate given orally, n = 10). After 15 days of treatment; behavioral tests, blood tests, and histopathology samples were taken. Results: A significant improvement was observed in autism-like behaviors in rats treated with bismuth. Tumor necrosis factor-alpha (TNF-α), Interleukin-17 (IL-17), IL-6, prostaglandin E2 (PGE2), and malondialdehyde (MDA) levels decreased, and brain-derived neurotrophic factor (BDNF) levels increased in the bismuth group. Conclusion: This study showed that bismuth can be used in addition to other treatments for autism. However, further studies on the subject are needed.