To evaluate the relationship between pterygium and serum thyroid hormone, vitamin B12, vitamin D3, folic acid, and ferritin levels between pterygium patients and control and to assess its correlation with clinical findings. 18-65-year-old 100 pterygium patients and age and sex matched 60 healthy control subjects were included. The peripheric blood sampling results were investigated. Free triiodothyronine (FT3), free thyroxine (FT4), thyroid stimulating hormone (TSH), vitamin B12, vitamin D3, folic acid, and ferritin levels of pterygium and control groups were compared. FT3 level was higher in the patient group compared to the control group, while vitamin B12, vitamin D3, folic acid and ferritin levels were significantly lower in the patient group compared to the control group (p <
0.05) No significant difference was found between the patient and control groups in terms of age, gender and body mass index (BMI) (p = 0.295, p = 0.625, p = 0.547, respectively). This study reports that pterygium patients have lower serum vitamin B12, folic acid, ferritin and vitamin D3 levels than healthy individuals.