AIM OF STUDY: Thyroid Malignancy in multinodular goiter, STUDY DESIGN: Prospective observational study. PLACE & DURATION: Two years study from January 2010 to January 2012 was conducted in People's University of Medical and health sciences Nawabshah. PATIENTS & METHODS: The study comprises 100 patients. All were admitted from OPD. The patients were evaluated fully after history & examinations and specific investigations of thyroid profile, ultrasound, thyroid scan, FNAC, Biopsy, indirect laryngoscopy and general assessment. All patients with multinodular goiter were included and solitary nodule were excluded. Out of 100 patients 96 underwent surgery and tissue sent for histopathology. RESULTS: In this study of 100 patients of multinodular goiter, 82 (82%) were female and 18 (18%) were male. The maximum number of patients were in age group 15-75 years. Regarding the histopathological results 8 (8%) patients showed malignancy in multinodular goiter. Papillary carcinoma seen in 5 (5%), follicular carcinoma in 2 (2%) and 1 (1%) in anaplastic carcinoma. CONCLUSION: Thyroid malignancy is also seen in multinodular goiter, in which having a dominant nodule may lead to papillary, follicular and anaplastic carcinoma. Commonly treated with surgery by thyroidectomy and radioiodine substance.