Objective To investigate the feasibility of detection of epidermal growth factor receptor ( EGFR) exon 19 deletions and exon 21 L858R mutations in pleural effusion fromnon-small-cell lung cancer ( NSCLC) patients by mutant enriched PCR assay. Methods The mutations of exon 19 and 21 of EGFR gene in pleural samples fromthirty NSCLC patients were analyzed using both the mutant-enriched PCR assay and the non-enriched PCR assay. Results Ten ( 33. 3% , 10/ 30) exon 19 deletions and five ( 16. 7% , 5/30) exon 21 L858R mutation were detected by the mutant-enriched PCR assay, while only 6 cases ( 20. 0% ) and 1 case ( 3. 3% ) were detected by the non-enriched PCR assay respectively. The difference of mutation detection rate of EGFR gene between the two methods was statistically significant ( P = 0. 032) . Mutations were detected in all of partial responders ( 2 /4) among the four patients who received gefitinib therapy. Conclusions Mutant-enriched PCR assay can detect EGFR exon 19 deletions and exon 21 L858R mutation in pleural effusion from NSCLC patients effectively, economically and accurately. It may be a valuable biomarker for gefitinib therapy in advanced NSCLC.