Estimating the value of our preoperative workup in the treatment of patients with clinically N0 (cN0) squamous cell carcinoma of the oral cavity. Retrospective analysis. Results of preoperative palpation, ultrasound (US) and ultrasound-guided fine needle aspiration cytology (FNAC) were compared to the histological findings after unilateral or bilateral elective selective neck dissection of level I-III (SND I-III) in patients with cN0 squamous cell carcinoma of the oral cavity. Occult metastases were detected by in 50 (22%) out of the 224 cN0 patients. No metastases were found beyond level III in extended neck dissections. T1N0M0 tumors and T2N0M0 tumors metastasized in 8 out of 77 cases (10%) and 32 out of 112 (29%) cases, respectively. Staging of the cN0 neck by palpation and US (+/-ultrasound-guided FNAC) missed occult lymph node metastases in 22% of the patients with oral cavity squamous cell carcinoma. The use of SND I-III therefore still is warranted. Frozen section sampling seemed to be redundant in this selected group of patients, because no additional metastases were found in extended neck dissection specimens. It might not be necessary to perform elective neck dissection in patients with T1 tumors.