The indications for and extent of routine lymph node dissection in patients with papillary thyroid carcinoma (PTC) are unclear. The aim of this study was to investigate the association between the extent of central lymph node dissection (CLND) and the therapeutic effects and potential risks in patients with a small PTC. A total of 103 patients with a PTC <2 cm who underwent total thyroidectomy with routine CLND were divided into those who underwent routine bilateral CLND (group I) and those with ipsilateral CLND (group II). Therapeutic efficacy was evaluated by the extent of lymph node metastasis and postthyroidectomy serum thyroglobulin concentration. Patients with postoperative symptomatic hypocalcemia were considered to have postoperative hypoparathyroidism and received calcium/vitamin D therapy. Altogether, 12 of 21 patients (57.1%) in group I and 48 of 75 (64.0%) in group II had postthyroidectomy serum thyroglobulin concentrations <1.0 ng/ml; furthermore, 17 of 21 (81.0%) in group I and 60 of 75 (80.0%) in group II had concentrations <2.0 ng/ml. Hypocalcemia symptoms were identified in 12 of 25 patients (48.0%) in group I and in 16 of 78 (20.5%) in group II (p = 0.009). The extent of the CLND did not influence the therapeutic effects in patients with small PTCs, but those who underwent bilateral CLND showed an increased rate of transient hypoparathyroidism. These findings indicate that the more conservative routine CLND is as safe as more extensive CLND for patients with a small PTC.