Aim: To evaluate the role of Fine Needle Aspiration Cytology in Diagnosis of Thyroid lesion. Materials and Methods: A retrospective research was conducted at the Department of Pathology, Assiut University and Hospital, Egypt. An overall total of 200 patients with a single thyroid nodule who met the inclusion criteria were included in the research. In the case of fine needle aspiration cytology, the sensitivity, specificity, positive predictive value, and negative predictive value were determined based on histopathologic examination, which was the gold standard. Results: There were 120 females and 80 men in attendance, resulting in a female to male ratio of 1.5:1. The patients' ages varied from 14 to 71 years, with a mean age of 43.69 years plus standard deviation (12.49 years). The majority of the patients are between the ages of 30 and 40. Neck oedema was the most common symptom among these patients (100 percent), followed by vocal cord palsy (15 percent), breathing difficulties 11 percent, and dysphagia 9 (4.5 percent), respectively. The thyroid nodule varied in size from 2 to 6.9 cm, with a mean of 4.51 +/- S.D. 1.89 cm and a standard deviation of 1.89 cm. Based on the results of this study, nodular goitre accounted for 52 percent of solitary thyroid nodules, with benign cyst accounting for 32 percent of benign lesions, 33 percent of follicular carcinoma, 17 percent of papillary carcinoma, and three cases being suspicious of neoplasm among the benign lesions. Conclusion: FNAC has key rule in diagnosis of solitary thyroid nodule because it is safe, minimally invasive and cost effective diagnostic tool.