Background:to compare intraocular pressure (IOP) changes (ΔIOP) between obese patients and normal weight controls in relation to different positions: standing, sitting and supine. Subjects and Methods: Patients candidates for bariatric surgery and normal weight controls. IOP was measured both in patients and controls with Tono-Pen AVIA in different positions. The utilized sequence was: after 5 minutes (5’) in standing position, sitting, supine, 5’supine, and immediately after standing. ΔIOP obtained by supine positions and all other positions were therefore evaluated. Results: Ninenty-two eyes of 46 obese patients (14 males) with an age between 18 and 59 years (mean 38.07±11.51 years) and BMI between 31.84 and 60.65 (mean 41.84±7.05) were evaluated. Forty-eight eyes of 24 normal weight controls (5 males) aged between 23 and 55 (mean 35.21±11.96 years) and BMI between 18.20 and 26.79 (mean 21.04±2.36) were also recruited. In obese patients there were statistically significant differences between IOP in supine position and supine positions 5’ with all other IOP measurements (all P<0.05). There were statistically significant differences between ΔIOP in both supine positions and prolonged standing positions obtained by patients and controls. (P<0.05). Conclusions: In obese patients there is a statistically significant increase in IOP in the supine positions that is significantly greater than normal weight population. BMI is weakly correlated with IOP and ΔIOP in postural changes.