Objective: To assess corneal Langerhans cell (LC) density in thyroid-associated ophthalmopathy (TAO) patients to evaluate the role ofinflammation in ocular surface disease related to TAO by using in vivo confocal microscopy (IVCM).Methods: Thirty-three patients who had inactive disease [(Clinical Activity Score (CAS)<3] and thirty age-matched healthy control subjects wereenrolled in the study. All subjects underwent routine ophthalmologic examination including visual acuity levels, intraocular pressure, anteriorsegment, and posterior segment evaluation. The subjects were evaluated with tear break-up time (BUT). IVCM was performed to assess LC densityin the central cornea. Also, correlation analyses of LC density and clinical data were performed.Results: The mean BUT was 9.61±5.01 seconds in the TAO group and 12.70±2.76 seconds in the control group (p=0.003). The median centralcorneal LC density in the control group was 19.00 (7.00-24.50) whereas it was significantly increased to 68.00 (50.00-92.00) in the TAO patients(p<0.001). In correlation analysis, there was a significant negative correlation between age and CAS of TAO patients (r=-0.348, p=0.047), and theage of TAO patients was not correlated with BUT and LC count (r=0.236, p=0.186 and r=-0.211, p=0.240, respectively). BUT of TAO patients wasnegatively correlated with LC count and CAS (r=-0.495, p=0.003 and r=-0.644, p<0.001, respectively). The CAS of the patients was not correlatedwith the LC count of the patients (r=0.261, p=0.143). In the control group, BUT, CAS and LC count was not correlated with each other.Conclusion: TAO patients in the inactive phase suffer from ocular surface inflammation and LC participates in corneal inflammation in TAO.