P apillary thyroid carcinoma (PTC) is the most common endocrine malignancy. [1] The incidence of papillary thyroid cancer is increasing tremendously in developed countries, mostly because of the determination of intrathyroidal papillary microcarcinomas that has led to suspects regarding overdiagnosis and overtreatment. [2][3][4] The incidence of thyroid carcinoma increased by three-fold between 1975 and 2009 in the US and was reported to be 15 times greater in 2011 than in 1993, which is mainly due to the initiation of a national cancer research program, in South Korea. [5,6] Although the prevalence of clinically diagnosed PTC is 1%, the prevalence of occult papillary carcinoma reaches up to a rate of 35.6% in the general population at autopsies. [7] However, despite the sudden increase in thyroid cancer, cancer mortality did not increase. [5,6] Papillary thyroid microcarcinomas (PTMCs) are tumors with Papillary thyroid carcinoma is the most common endocrine malignancy. Papillary thyroid microcarcinomas (PTMCs) are tumors with a size of ≤1 cm. The biological behavior of these tumors differs due to the presence of their aggressive features. The prognosis of PTMCs with high-risk features, such as clinical node metastasis, distant metastasis, and significant extrathyroidal extension to the tracheal or recurrent laryngeal nerve invasion, is poor, even if a sufficient immediate surgery is performed at diagnosis. However, PTMCs without these aggressive features are low-risk tumors because of their indolent and slow growth behaviors. The increase in thyroid cancer incidence is mostly a result of overdiagnosis of small low-risk PTMCs with indolent clinical course. Despite the sudden increase in thyroid cancer incidence worldwide, cancer mortality did not increase. Although the traditional treatment strategy for PTMC is immediate surgery at diagnosis, because of the rather low disease-specific mortality rate, low recurrence rate, and potential risk for postoperative complications, active surveillance has been proposed recently as an alternative option for PTMCs without invasion, metastasis, or cytological or molecular characteristics. The recent data support that active surveillance of low-risk PTMC should be the initial treatment modality, because only a small percentage of low-risk PTMCs show signs of progression, and delayed surgery has not caused significant recurrence. However, recent management guidelines are shifting toward more conservative treatments, such as active surveillance. Although there is an increase in the number of studies related to active surveillance, prospective studies have been mostly from academic referral centers in Japan. The world still needs class 1 evidence extended prospective studies originating from different geographic regions. Active surveillance may be a good alternative to immediate surgery for appropriately selected patients with PTMC.