['Lymph node metastasis is the mayor cause of mortality in patients with head and neck squamous cell carcinomas (45%). The genetic changes underlying metastasis are still largely unknown and genetic markers to predict lymph node positivity still need to be found. The aim of this study was to search such markers by using Multiplex Ligation-dependent Probe Amplification (MLPA), a semi-quantitative PCR technique to detect gene copy number alterations.', 'Thirty-seven genes were analysed by MLPA in 34 larynx and 22 pharynx carcinomas.', 'Losses of CDKN2A (9p21) and MLH1 (3p22) and gains of CCND1, EMS1 (both at 11q13), RECQL4 and PTP4A3 (both at 8q24) were the most frequent aberrations in both larynx and pharynx carcinomas. Amplifications were detected at EMS1, CCND1 and ERBB2 (17q21). A correlation between loss of N33 (8p22) and poor survival was found (p=0.02). Gain of EMS1 had the same relation with survival but not significant (p=0.08). Lymph node positive tumors presented a specific pattern of genetic alterations, with losses of N33, STK11 (19p13) and TP53 (17p13), the latter especially in larynx tumors.'] Are deletions of N33 , STK11 and TP53 involved in the development of lymph node metastasis in larynx and pharynx carcinomas?