The aim of this study was to evaluate the correlation between central lymph node (CLN) metastasis and Clinicopathological characteristics of papillary thyroid cancer (PTC). In addition, we investigated the incidence and risk factors for ipsilateral and contra lateral CLN metastasis in unilateral PTC and the appropriate surgical extent for CLN dissection. A prospective study of 143 patients with unilateral PTC who underwent total thyroidectomy and prophylactic bilateral CLN dissection was conducted. Of 143 patients, 58 had CLN metastases. The rate of CLN metastasis was considerably higher in cases of maximal tumor size > 1 cm ( < 0.0001; OR 5.81). Ipsilateral CLN metastasis was detected in 41% of cases of unilateral PTC, and contra lateral CLN metastases was found in 14% of cases where as bilateral CLN metastases in 8% of cases. The rate of contra lateral CLN metastasis was considerably higher in cases of PTC with a large tumor size (≥ 1 cm) ( = 0.0003; OR = 0.144) and with ipsilateral CLN metastasis ( = 0.0002; OR 0.12). Tumor size > 1 cm was independent risk factors for CLN metastasis. Maximal tumor size > 1 cm and presence of ipsilateral CLN macro metastasis were independent risk factors for contra lateral CLN metastasis. Therefore, both ipsilateral and contra lateral CLN dissections should be considered for unilateral PTC with a maximal tumor size > 1 cm or presence of ipsilateral CLN macro metastasis.