INTRODUCTION: Randomized controlled trials (rcts) are the "gold standard" for establishing treatment efficacy; however, efficacy does not automatically translate to a comparable level of effectiveness in routine practice. Our objectives were to □ describe outcomes of palliative platinum-doublet chemotherapy (ppdc) in non-small-cell lung cancer (nsclc) in routine practice, in terms of survival and well-being; and□ compare the effectiveness of ppdc in routine practice with its efficacy in rcts. METHODS: Electronic treatment records were linked to the Ontario Cancer Registry to identify patients who underwent ppdc for nsclc at Ontario's regional cancer centres between April 2008 and December 2011. At each visit to the cancer centre, a patient's symptoms are recorded using the Edmonton Symptom Assessment System (esas). Score on the esas "well-being" item was used here as a proxy for quality of life (qol). Survival in the cohort was compared with survival in rcts, adjusting for differences in case mix. Changes in the esas score were measured 2 months after treatment start. The proportion of patients having improved or stable well-being was compared with the proportion having improved or stable qol in relevant rcts. RESULTS: We identified 906 patients with pre-ppdcesas records. Median survival was 31 weeks compared with 28-48 weeks in rcts. After accounting for deaths and cases lost to follow-up, we estimated that, at 2 months, 62% of the cohort had improved or stable well-being compared with 55%-63% who had improved or stable qol in rcts. CONCLUSIONS: The effectiveness of ppdc for nsclc in routine practice in Ontario is consistent with its efficacy in rcts, both in terms of survival and improvement in well-being.