Abstract Background Among the most commonly observed bleeding disorders in children is immune thrombocytopenia (ITP). Many autoimmune diseases have been successfully treated with probiotics, which can also play a role in the regulation of immune responses. This study was conducted to assess the impact of probiotics as adjunct treatment for children with newly diagnosed ITP. Methods This randomized controlled trial was conducted on 60 children with newly diagnosed ITP who were allocated into 2 groups, group I the control group (n = 30), receiving standard corticosteroid therapy (prednisone 2 mg/kg/day for 1 week), group II the probiotic group (n = 30), receiving standard corticosteroid therapy (prednisone 2 mg/kg/day for 1 week) plus probiotics (Bacillus clausii, 2 billion/5 ml daily for 2 weeks). Platelet counts, bleeding scores, and side effects were assessed over a 12-months follow-up period. Results The probiotic group showed significantly higher platelet counts at 6 and 12 months compared to the control group (p