There are no agents labelled for use as fourth-line therapy for non-small-cell lung cancer, even though it is currently prescribed in about 5-10% of patients. Here, we provide a pooled analysis of published studies on the efficacy of treatments in patients who have had at least three unsuccessful lines of therapy. The literature search was performed on Pubmed, EMBASE, the Web of Science, SCOPUS, CINAHL, Google Scholar and the Cochrane Library using the terms 'lung cancer' OR NSCLC AND 'fourth line'. The response rates and disease control rates were pooled using a random-effect or a fixed-effect model according to heterogeneity. Median progression-free survival and overall survival data were also collected and aggregated to obtain pooled median values of the included studies. Overall, 14 studies (673 patients), which were almost entirely published by Asian institutions, were eligible for this pooled analysis. Among these were two phase II trials and 12 retrospective cohort series. In general, the pooled overall response rate was 13.6% [95% confidence interval (CI) 10-18.3] and the pooled overall disease control rate was 47.3% (95% CI 38-56.9). The pooled median progression-free survival for these studies was 3.34 months (95% CI 2.42-4.27). The pooled median overall survival for these studies was 10.5 months (95% CI 9.57-11.52). In conclusion, for non-small-cell lung cancer patients who have undergone three or more unsuccessful lines of therapy, fourth-line treatment could be offered in select cases to those with a good performance status.