Many of the physiologic changes that occur during acute and chronic altitude exposure may actually negate adaptations that possibly improve physiologic performance upon return to sea level. We aimed to determine the effects of hypobaric hypoxic conditions at mid-altitude on mental performance by psychometric tests. This study was performed on 34 male volunteer mountaineers coming from different regions of Turkey. Their mean ages, heights and weights were 33.5 +/- 11.8 years, 176.4 +/- 8.2 cm and 73.0 +/- 10.5 kg, respectively. These tests were carried out on volunteer climbers firstly at the residence center at altitude of 1200 in (Hacilar, n = 34), and secondly on the same day at altitude of about 2850 in after 4 h from firstly (base camp at Mount Erciyes, n = 34), and then finally psychological tests were done at altitude 3900 in after one day from secondly (n = 31). State (acute) and trait (chronic) anxieties scales, and short symptom inventory tests were applied to 34 male volunteer mountaineers at three different altitudes. Although trait and state anxiety scores decreased at two different altitudes, this difference was not statistically significant (p > 0.05). But the trait and state anxiety scores at Erciyes summit increased (p < 0.05). The findings of somatization, obsessive-compulsive disorders, interpersonal sensitivity, anxiety disorder, hostility, phobic anxiety, paranoid ideation and psychoticism, additional materials index, scores increased at summit and were found statistically significant (p < 0.05). Global indexes that is seriousness of disturbance index, total symptom index and symptom disturbance index scores in the Erciyes summit increased significantly (p < 0.05). But total symptom index scores decreased significantly at Erciyes base camp (p < 0.05). Although all psychometric test scores decreased in base camp area, all findings increased significantly at Erciyes Mountain Summit. We considered that general characteristics of hypobaric hypoxic conditions and environmental factors might cause emotional and behavioral changes on individuals depending on psychological and physiological features.