Molecular targeted therapy based on tyrosine kinase inhibitors (TKI), directed at epidermal growth factor receptor (EGFR) is one of the novel effective agents in management of advanced-stage of Non Small Cell Lung cancer (NSCLC). However several candidate predictors have been extensively studied, apart from activating EGFR gene mutations, no reliable biochemical or molecular predictors of response to erlotinib have been validated. The aim of our retrospective study was to evaluate the association of baseline serum albumin with outcomes in a large cohort of patients with advanced-stage NSCLC treated with erlotinib. Clinical data of 457 patients with locally-advanced (III B) or metastatic stage (IV) NSCLC treated with erlotinib were analysed. Serum samples were collected and the measurement was performed one day before the initiation of erlotinib treatment. Before the treatment initiation, low albumin was (<35 g/l) measured in 37 (8.1%) patients and normal albumin (≥ 35 g/l) was measured in 420 (91.9%). The median PFS and OS for patients with low serum albumin was 0.9 and 1.9 months compared to 1.9 and 11.4 months for patients with normal serum albumin (p=0.001 and p<0.001). The multivariate Cox proportional hazards model revealed that EGFR mutation status (HR=2.50; CI: 1.59-3.92; p<0.001) and pretreatment serum albumin (HR=1.73; CI: 1.21-2.47; p=0.003) were significant independent predictive factors for PFS, whereas EGFR mutation status (HR=3.14; CI: 1.70-5.81; p<0.001), stage (HR=1.48; CI: 1.09-2.02; p=0.013), ECOG PS (HR=1.77; CI: 1.37-2.29; p<0.001) and pretreatment serum albumin (HR=4.60; CI: 2.98-7.10; p<0.001) were significant independent predictive factors for OS. In conclusion, the results of present retrospective study indicate that pretreatment hypoalbuminemia is associated with poor outcome of NSCLC patients treated with erlotinib. Based on these results, measuement of serum albumin is an objective laboratory method feasible for estimation of prognosis of patients with advanced-stage NSCLC.