Hypermethylation has been shown in the promoter region of the endothelin receptor B (EDNRB) gene in several human tumors, but its role in lung cancer formation is unclear. In this study, genomic DNA from lung cancer patients was subjected to methylation-specific PCR to determine the methylation status of the EDNRB gene in lung cancer. Aberrant methylation of the EDNRB gene was detected in 32.9% (26 of 79) lung cancer patients. Promoter hypermethylation of EDNRB was found to significantly differ with histological type but was not correlated to other clinicopathological characteristics. Decreased mRNA transcripts were correlated to aberrant methylation. Treatment with 5-aza-deoxycytidine reversed the methylation status and re-expression of the EDNRB gene in the H1355 human lung cancer cell line. Our results suggest that inactivation of the EDNRB gene through epigenetic alteration is highly prevalent in lung cancer in Taiwan.