Background <p>Coronary artery ectasia (CE) is the most severe complication in children with Kawasaki disease (KD) and increases the risk of long-term cardiovascular events This study aims to investigate the effects of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and procalcitonin (PCT) on KD children, as well as the discriminative ability of these biomarkers for identifying CE.</p> Methods <p>A total of 130 KD children were recruited as research subjects, consisting of 65 cases without CE (KD-nCE group) and 65 cases with CE (KD-CE group). The differences in baseline clinical information and complete blood count between the KD-nCE and KD-CE groups were analyzed using chi-square tests and t-tests. The correlations of CRP, ESR, and PCT with the coronary artery inner diameter were evaluated using Spearman and Pearson methods. The relationships between CRP, ESR, and PCT and the development of CE in KD children were determined using logistic regression and receiver operating characteristic (ROC) curves.</p> Results <p>The serum levels of WBC, PLT, CRP, ESR, and PCT were higher in the KD-CE group than in the KD-nCE group. Moreover, serum CRP, ESR, and PCT levels showed potential correlations with the coronary artery inner diameter in KD children. CRP, ESR, and PCT levels were identified as factors associated with the development of CE in KD children, and elevated levels of these three biomarkers were related to an increased likelihood of CE.</p> Conclusion <p>Serum levels of CRP, ESR, and PCT are correlated with the presence of CE in KD patients, and the combined assessment of these three biomarkers may provide discriminative value for identifying CE in KD.</p>