Direct bioimpedance measures (resistance, reactance, phase angle (PA)) determined by bioelectrical impedance analysis (BIA) detect changes in tissue electrical properties. The study was conducted to evaluate soft tissue hydration and mass through pattern analysis of vector plots as height, normalized resistance, and reactance measurements by bioelectric impedance vector analysis in patients with head and neck cancer. Whole-body measurements were made with ImpediMed bioimpedance analysis in 56 adult, white, male subjects 42 to 79 years old: 28 patients with head and neck squamous cell carcinoma (H&NC) and 28 healthy volunteers matched by sex, age and BMI as a control group. All patients were previously untreated and without active nutritional interventions. Mean vectors of H&NC group vs. the control group were characterized by an increased normalized resistance component with a reduced reactance component (separate 95% confidence limits, P<0.05), indicating a decreased ionic conduction (dehydration) with loss of dielectric mass (cell membranes and tissue interfaces) of soft tissue. Monitoring vector displacement trajectory toward the reference target vector position may represent useful feedback in support therapy planning of individual patients before surgery in patients with head and neck cancer in order to reduce post-operational complications.