The aim of the study was to evaluate whether pretherapeutic metabolic tumor parameters from 18-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging could predict larynx preservation in laryngeal and hypopharyngeal cancer patients prior to primary chemoradiation. Tumor metabolic parameters [maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG)] were retrospectively assessed in a consecutive cohort of laryngeal and hypopharyngeal cancer patients undergoing primary (chemo-)radiation. Main outcome measures were larynx preservation and survival. The study included 97 patients with a median follow-up of 32 months (IQR 20–54.5). For hypopharyngeal cancer, multivariable analysis showed that patients with a primary tumor’s SUVmax > 9.5 entailed a higher risk of undergoing salvage pharyngolaryngectomy after chemoradiation (HR = 8.64, 95% CI = 1.1–67.3, P = 0.040). In laryngeal cancer, SUVmax did not predict the need for salvage laryngectomy. The only predictor for larynx preservation in laryngeal cancer patients was T-classification at initial diagnosis (HR = 6.67, 95% CI = 0.82–53.9, P = 0.039). In conclusion, SUVmax of primary tumor could be used as a predictor of larynx preservation prior to primary chemoradiation in hypopharyngeal cancer patients. This information may be important for patient counseling, as high SUVmax was correlated with reduced probability of larynx preservation. However, in laryngeal cancer patients, SUVmax does not seem to be predictive of outcome.