['The purpose of this study was to determine whether the recommended waiting period of 3 months is necessary for repeat fine-needle aspiration biopsy (FNAB).', 'A retrospective review of 128 nodules from 126 patients with initial nondiagnostic (ND) results was performed for the period between January 2009 and December 2012. Demographic and clinical factors were recorded including age, sex, time interval between FNABs, and ultrasound (US) factors, i.e. nodule size, location, consistency, suspicious malignant findings and thyroiditis. The time interval was subdivided into </≥5, 10, 15 and 20 weeks after the initial FNAB. The effects on the nuclear atypia were analyzed using the Fisher exact test and the Mann-Whitney U test.', 'None of the demographic, clinical or US variables was significantly related to the atypical diagnosis of repeat FNAB. The time interval until repeat FNAB was also not related to the atypical diagnosis (p = 0.63, 0.57, 0.23 and 0.48 for 5, 10, 15 and 20 weeks, respectively).'] Does repeat Fine-Needle Aspiration Biopsy within a Short Interval Increase the Atypical Cytologic Results for Thyroid Nodules with Previously Nondiagnostic Results?