Conjugated fatty acids were known as potential sources for the pharmaceutical industry with beneficial bioactivities, including anti-cancer effects, anti-diabetes, anti-obesity, and anti-inflammatory properties. In the present work, characteristics of triglycerides and fatty acids of the seed oils of five plants (Momordica Cochinchinensis (Lour.) Spreng, MomordicaMomordica charantia, Thladiantha nudiflora Hemsl, and Trichosanthes cucumerina var. anguina) in Vietnam were analyzed by UV and FTIR spectroscopy, and reversed phase high performance liquid chromatography. Triacylglycerides compositions of the seed oils were determined using RP-HPLC with DAD detector connected with MS detector in series. The seed oils of M. Cochinchinensis, M. subangulata, and M. charantia are rich sources of conjugated octadecatrienoic acid with α-eleostearic acid (C18:39E,11E,13Z) as the base acid and β-eleostearic as the minor conjugated acid. In the seed of Thladiantha nudiflora (both α-eleostearic and punic acid (C18:39Z,11E,13Z) were synthesized with approximately equal proportions. In T. cucumerina var. anguina seed oil, punicic acid was synthesized as the main conjugated fatty acid. In addition, some oil parameters, such as oil yield and refractive index of these seed oils, were determined.