Background <p>Immune thrombocytopenia (ITP) is an immune-mediated disorder marked by impaired self-tolerance, leading to accelerated platelet destruction, reduced platelet production, and a range of bleeding manifestations. This study aimed to evaluate the role of TIM-3 in children with newly diagnosed ITP.</p> Methods <p>This cross-sectional study included 80 children, comprising two equal groups. Group I consisted of children with newly diagnosed primary ITP, from whom samples were collected at diagnosis before treatment and again at remission (platelet count ≥ 100 × 10⁹/L with resolution of bleeding symptoms after treatment). Group II included age, and sex matched healthy children serving as controls.</p> Results <p>TIM-3 levels were significantly and positively correlated with platelet counts at both diagnosis and remission (<i>P</i> &lt; 0.05), while showing a significant negative correlation with bleeding scores (<i>P</i> ≤ 0.001). Hemoglobin levels increased markedly after remission compared with diagnosis. White blood cell counts at diagnosis differed highly significantly between patients and controls (<i>P</i> ≤ 0.001), and TIM-3 levels at diagnosis were significantly lower in the ITP group than in healthy controls.</p> Conclusions <p>This study assessed TIM-3 role in newly diagnosed children with ITP. According to the results, TIM-3 could affect the immune response and platelet destruction in individuals with ITP, suggesting a key function for this protein in the disease’s pathophysiology.</p> Trial registration <p>Not applicable.</p>