Functional independence in glioblastoma (GBM) patients is a key factor in measuring the quality of life. Progression free survival (PFS) and overall survival (OS) have been largely described. However, the evolution over time of the performance status during the patients' life remains understudied. We thus studied the time to loss of functional independence as assessed by a Karnosky Performance Status (KPS) below 70 % in GBM patients. We analysed all GBM patients treated in our institution between 2008 and 2013 and meeting the following criteria: age >18 years, supratentorial location, post-surgical KPS ≥ 70 %, initially treated with concomitant radiotherapy (RT) and Temozolomide. Within the 84 patients studied, the median PFS was 9 months and the median OS was 18.7 months. The median survival time with functional independence (KPS ≥ 70 %) was 14.5 months. On average, the patients spent 73 % of their lifespan with a KPS ≥ 70 %. Surgical resection and low steroid dosage were statistically associated with increased survival time with KPS ≥ 70 % (p = 0.015 and p = 0.03, respectively). Sixty-two (62) patients received one or several lines of chemotherapy at recurrence. Under treatment with Bevacizumab (42 Bev-based regimens), radiological responses were seen in 35 % and improvement in KPS occurred in 24 % whereas no response and rare improvement of KPS (3 %) were seen with other type of chemotherapy (97 non Bev-based regimens). In GBM patients, median survival with KPS ≥ 70 % largely exceeds PFS. Surgical resection and low steroids dosage at RT-onset appeared as good prognosis factors for survival with functional independence.