Dehydrocorydaline was isolated from the roots of Corydalis ternata (Papaveraceae) and identified by the comparison the $^1H-$ and $^{13}C$-NMR spectral data with those of authentic sample. The content of dehydrocorydaline was determined by the HPLC analysis based on extraction of ground plant material. Quantitative analysis of dehydrocorydaline in MeOH extract of C. ternata by HPLC showed $1.31{pm}0.95%$ in 20 samples collected throughout regions of Korea.