Background: Tooth movement can be classified into physiological tooth movement and orthodontic tooth movement (OTM). The humoral arm of the innate immune response includes components of the complement cascade and soluble pattern recognition molecules (PRM), particularly collectins (surfactant protein-A, [SP-A], and SP-D), ficolins, (ficolin-1;−2;−3) and members of the pentraxin family (C-reactive protein [CRP], serum amyloid P component [SAP], and long pentraxin 3 [PTX3]). Hence; the present study was conducted for assessing the Pentraxin-3 levels during orthodontic tooth movement in patients undergoing fixed orthodontic treatment. Materials & methods: A total of 20 patients were enrolled in the present study which was scheduled to undergo fixed orthodontic treatment. Collection of GCF and estimation of PTX-3 levels was done at baseline, 4 hours after starting of fixed orthodontic treatment, 24 hours after starting of fixed orthodontic treatment, and 1 week after starting of fixed orthodontic treatment. Collection of GCF was done from the mesial side of maxillary canines. Isolation of the area was done with the help of cotton rolls. The GCF was collected with paper strips inserted into the crevice until mild resistance was felt and left there for 30 seconds. All the samples were sent to laboratory where an auto-analyser was used for evaluation of PTX-3 levels. Results: Mean PTX-3 levels at Baseline, 4 hours after starting of fixed orthodontic treatment, 24 hours after starting of fixed orthodontic treatment and 1 week after starting of fixed orthodontic treatment were found to be 0.95 ng/ml, 1.28 ng/ml, 2.45 ng/ml and 1.2 ng/ml respectively. While analysing statistically, it was observed that mean PTX-3 levels increased significantly till 24 hours after starting of the fixed orthodontic treatment to three times of its baseline values, and further declining significantly to its baseline range at 1 week after starting of fixed orthodontic treatment. Conclusion: Significant alteration of PTX-3 levels in the GCF does occur during the course of orthodontic treatment highlighting the role of inflammation in orthodontic tooth movement. Key words: Pentraxin, Orthodontic treatment