Background and aim of the work: Recent studies revealed that hypobaric hypoxia stimulates release of vascular endothelial growth factor (VEGF) and other studies found that high levels of this angiogenic factor are correlated with poor prognosis in patients with non-small cell lung cancer (NSCLC). In this study we will measure the serum levels of VEGF in both healthy individuals and in patients with operable non small cell lung carcinoma living in hypobaric oxygen environment (Taif) and validate the prognostic significance of its pretreatment level in those patients. Patients and methods: Thirty one patients with operable (stage I, II and III A) non-small cell lung cancer (the patient group) and 15 healthy volunteers with matched gender and age (control group) were enrolled in this study from January 2010 to March 2015. The pretreatment level of VEGF was measured in patients in addition of its level in controls. All patients had the same diagnostic and therapeutic protocols. Mean follow up of patients was 30.4±7.8 months. Results: Themean level of VEGF was high in control group, however, it was significantly lower than that in patient group (P value 0.041). The median survival of stage I patients was 13 months, stage II was 9 months, and of stage III A was 6 months. Univariate analysis showed a significant correlation between survival and pretreatment level of VEGF in patients with small lung cancer. Conclusions: Our results revealed that hypobaric hypoxia significantly increases the circulating levels of VEGF in healthy individuals without remarkable effect on its level in patients with NSCLC. Our study verified also that the pretreatment mean serum level of VEGF showed a highly significant increase in NSCLC patients than that in control group and it was significantly correlated with patient survival in levels above 618 pg/ml.