Solitary thyroid nodule (STN) is a common thyroid disorder. Clinically recognized thyroid carcinoma constitutes less than 1% of human malignant tumours. The risk of malignancy in solitary thyroid nodule is greater than other thyroid swelling. The risk of malignancy in generalized thyroid swelling is about 3% and in solitary thyroid nodule it is about 15%. This study was carried out in Surgery and ENT Department, Mymensingh Medical college Hospital from November 2008 to October 2009 to see pattern of malignancy in clinically solitary thyroid nodule. Total 108 patients of STN was included in this study, majority of the patients were within 20-39 years age group with female predominance. In addition to thyroid swelling some patients presented with other symptoms like cervical lymphadenopathy in 6(5.56%), dysphagia 2(1.85%), hoarseness of voice 2(1.85%) and metastatic lesion in bone 1(0.92%) cases. Among 108 cases of solitary thyroid nodule only 19 cases were malignant. Patients with malignant lesion presented with shorter duration of symptoms. Out of 19 malignant cases 6(31.58%) cases presented with features of metastasis. Malignancy was more predominant in male (25.00%) than the female (14.47%) in STN. Out of 19 malignant cases, 12(63.16%) were papillary carcinoma, 5(26.31%) were follicular carcinoma and 2(10.53%) cases were medullary carcinoma. Study showed significant difference (p<0.01) between papillary & follicular carcinoma and significant difference (p<0.001) between papillary & medullary carcinoma. Papillary carcinoma was most common among all thyroid malignancies in patients with solitary thyroid nodule.