INTRODUCTION: Thyroid nodules are a common diagnostic challenge mainly because of the need to exclude thyroid malignancy. The aim of this study was to evaluate the usefulness of demographic, ultrasonographic and scintigraphic findings in differentiating benign from malignant thyroid lesions in patients presenting with thyroid nodules.MATERIALS AND METHODS: 941 patients, who presented with palpable thyroid nodules and underwent at least one fine-needle aspiration biopsy (FNAB), were retrospectively evaluated.RESULTS: The thyroid was assessed by ultrasonography (US) in 796 patients and by scintigraphy (SC) in 774 patients. The final diagnostic outcome was established after surgery (n=183) or after a minimum of one-year clinical follow-up period. Higher rates of malignancy were observed in male gender (p<0.001), in patients presenting with a solitary nodule in US (p<0.001), in nodules with maximum diameter > or =4.5 cm in US (p=0.024) and in nodules detectable by SC (p=0.006). There were no statistical differences in the rates of malignancy among cystic, solid or mixed nodules in US or among "hot", "warm" or "cold" nodules in SC.CONCLUSIONS: Male gender, solitary nodule and nodule diameter > or =4.5 cm can serve as adjuncts to FNAB in predicting the risk of thyroid malignancy in patients presenting with thyroid nodules.