In primary squamous cell carcinoma (SCC) of the oral cavity, many clinical and histopathological factors have been described as predictive for cervical lymph-node metastasis, but there are no data available on this association for surgical resection of lateral tongue primary SCC. The aim of this study was to analyse factors related to contralateral neck relapse in a series of 203 consecutive patients with SCC of the lateral aspect of the tongue treated by surgery with or without adjuvant radiotherapy. Several clinical features were analyzed. Histological study included pTNM classification, tumour size, surgical margins, extracapsular spread of lymph-node metastasis, perineural infiltration, peritumoral inflammation and bone involvement. The mean duration of follow up for surviving patients was 70.9+/-49.6 months; 47 patients eventually died of the disease and 116 patients are alive with no evidence of recurrence. The mean disease-specific survival time was 149+/-7 months. Twenty (9.8%) patients developed ipsilateral and nine (4.4%) contralateral neck recurrence. The mean period of time from surgery to contralateral neck recurrence was 11.4 months (range 3-27 months). Fourteen of the 20 ipsilateral and 8 of the 9 contralateral neck relapse patients eventually died of the disease. Histopathological grading and peritumoral inflammation were found to be statistically significant (P<0.05). Clinical and pathological lymph neck node status was not found to be associated with the appearance of contralateral lymph neck node relapse. Due to the increased risk of contralateral neck relapse within the first 2 years of surgery, close surveillance is mandatory at this time.