Tissue factor pathway inhibitor-2 (TFPI-2) is a major inhibitor of extracellular matrix degradation. Decreases in TFPI-2 contribute to malignant tumor cell production, and TFPI-2 is a presumed tumor suppressor. TFPI-2 gene transcription is regulated by two epigenetic mechanisms: DNA methylation of the promoter and K4 methylation of histone 3 (H3). Lysine-specific demethylase 1 (LSD1) and LSD2 demethylate H3K4me2/1. LSD1 has been implicated in TFPI-2 regulation through both epigenetic mechanisms, but the involvement of LSD2 remains unknown. We prepared a monoclonal anti-LSD2 antibody that clearly distinguishes LSD2 from LSD1. Knockdown of LSD1 or LSD2 by siRNAs increased TFPI-2 protein and mRNA. Simultaneous knockdown of both LSD1 and LSD2 showed additive effects. Bisulfite sequencing revealed that CpG sites in the TFPI-2 promoter region were unmethylated. These results indicate that LSD2 also contributes to TFPI-2 regulation through histone modification, and that further studies of the involvement of LSD2 in tumor malignancy are warranted.