The objective of this research is to use metabolomic techniques to discover and validate plasma metabolite biomarkers for the diagnosis of early-stage non-small cell lung cancer (NSCLC). The study included plasma samples from 156 patients with biopsy-confirmed NSCLC along with age and gender-matched plasma samples from 60 healthy controls. A fully quantitative targeted mass spectrometry (MS) analysis (targeting 138 metabolites) was performed on all samples. The sample set was split into a discovery set and validation set. Metabolite concentration data, clinical data, and smoking history were used to determine optimal sets of biomarkers and optimal regression models for identifying different stages of NSCLC using the discovery sets. The same biomarkers and regression models were used and assessed on the validation models. Univariate and multivariate statistical analysis identified β-hydroxybutyric acid, LysoPC 20:3, PC ae C40:6, citric acid, and fumaric acid as being significantly different between healthy controls and stage I/II NSCLC. Robust predictive models with areas under the curve (AUC) > 0.9 were developed and validated using these metabolites and other, easily measured clinical data for detecting different stages of NSCLC. This study successfully identified and validated a simple, high-performing, metabolite-based test for detecting early stage (I/II) NSCLC patients in plasma. While promising, further validation on larger and more diverse cohorts is still required. Tissue Bank, which is the site of the Respiratory Health Network Tissue Bank of the Fonds de la Recherché du Quebec-Sante in Quebec, Canada. Dates of sample collection range from 2005 to 2017. Frozen (−80 • C) aliquots of 200-400 µL of plasma were assembled and shipped to The Metabolomic Innovation Centre (TMIC) at the University of Alberta, Canada for quantitative metabolomic analysis. The plasma samples were collected from 156 patients with biopsy-proven and biopsy-graded NSCLC and 60 healthy controls with comparable age and gender profiles. Healthy controls consisted of both smokers and non-smokers. The cancer samples had detailed data on cancer stage, lung cancer histology, age, weight, height, body mass index, smoking status (never/former/current), smoking history (cig/day and period of smoking in years), sex, survival history, medical condition history, personal history of cancer, lung disease status, treatment, tumor size (in mm), tumor grading, details of positive nodules, as well as data collected on each cancer patient's transthoracic needle biopsy, transbronchial biopsy, endobronchial biopsy, bronchoalveolar lavage, bronchial brushing, bronchial aspiration, endobronchial ultrasound, transesophageal echocardiography, bone scintigraphy, abdominal ultrasound, abdominal CT scan, thoracic CT scan, cerebral CT scan, thoracic X-ray, mediastinoscopy, thoracic MRI, cerebral MRI, and PET scan. Healthy controls had data on age, weight, height, body mass index, smoking status (never/former/current), smoking history (cig/day and period of smoking...