Defense mechanisms are automatic psychological processes that protect the individual against anxiety and from the awareness of internal or external dangers or stressors. The influence of defense mechanisms in patients on chronic hemodialysis treatment was studied. There were 53 uremic subjects (37 males and 16 females), aged between 22 and 88 years (mean age 60.11, SD 15.03), on chronic dialysis and 50 healthy subjects as controls have been enrolled in the study. According to the duration of dialysis, uremic patients were divided in two subgroups: 21 patients with less than 5 years and 19 patients with more than 10 years of dialytic treatment. Assessment was conducted using the Defense Mechanisms Inventory DMI. The inventory identifies five defensive styles: turning against the object (TAO), projection (PRO), principalization (PRN), turning against the self (TAS) and reversal (REV). Results showed DMI scores within the normal range both for uremics and controls with significant differences in TAO (t = -3.053, p = 0.003) and REV (t = 5.067, p < 0.0001) between groups. No significant differences in the use of defensive styles related to the duration of dialytic treatment were observed. Besides other psychological features, the assessment of defense mechanisms in patients with chronic and invalidating diseases may contribute to ameliorate the knowledge of the adjustment processes and of the psychological well-being of the patients.