BACKGROUND: Epidermal growth factor receptor (EGFR) mutation testing is recommended for selecting patients with non-squamous non-small cell lung cancer (NSCLC) for EGFR tyrosine kinase inhibitor drug treatment. OBJECTIVE: The objective of this article was to systematically review available evidence on the utilisation and determinants of EGFR mutation testing of patients with NSCLC in routine clinical practice. PATIENTS AND METHODS: Searches were made of five electronic databases (Web of Science, MEDLINE [Ovid], Science Direct, EMBASE and Scopus), bibliographies of relevant articles, studies that cited included studies and relevant cancer websites. Studies were included if they: (1) reported the rate of uptake of EGFR testing in patients with NSCLC; (2) were conducted in routine clinical practice settings; (3) were published in English prior to July 2017; and (4) had full text available. Studies were appraised using the STROBE and the National Institutes of Health (National Heart, Lung and Blood Institute) checklists. RESULTS: Eighteen eligible studies were identified for this systematic review, published between 2011 and 2017, from the USA (n = 7), Canada (n = 2), Republic of Korea (n = 2), Norway (n = 1), Sweden (n = 1), Germany (n = 1), Spain (n = 1), New Zealand (n = 1), China (n = 1) and multiple countries from the Asia-Pacific region (n = 1). Overall, testing for EGFR mutations was undertaken in 16,146 of 52,257 study patients (31%), although testing rates varied widely between different studies (from 7.8% to 78.3%). Single institution retrospective audits reported higher rates of testing (median 65.7%, range 31.3-78.3%) than population-based retrospective cohort analyses (median 23%, range 11-69%) and multi-institutional cross-sectional practitioner surveys (median 19.8%, range 7.8-31.8%). Nine studies reported increasing rates of testing over the study period but maximum testing rates remained less than 75% in most studies. Factors associated with higher testing uptake rates included: female sex; younger age; former/no smoking; advanced stage of lung cancer; adenocarcinoma histology; better mobility; radiation therapy; available tissue specimen; and private insurance. Among 16,146 tested patients, EGFR mutations were detected in 4328 patients (26.8%). However, estimates of mutation prevalence were biased by incomplete and selective testing in many studies. CONCLUSIONS: The uptake of EGFR mutation testing of patients with NSCLC is suboptimal in many parts of the world. Incomplete uptake of testing is fuelled by selective testing referral practices, sample limitations, and funding constraints.