Objectives: This study aimed to compare two Livistona species; Livistona decipiens Becc and Livistona australis Mart for their phenolic and carbohydrate contents and for their protective activity against ulcerative colitis. Methods: A high performance liquid chromatographic (HPLC) technique with inline connected to photo diode array detector (DAD) and electro array (EA) used for detection of the polyphenolic contents. Also HPLC with refractive index detection (HPLC-RI) was used to determine and to quantify carbohydrate contents before and after partial acid hydrolysis, using 0.2 N H₂SO₄, for 3 h at 100°C, for each of the defatted methanol extract concentrate. Protective activity against ulcerative colitis was evaluated by acetic acid inducing-ulcers method for both methanol extracts of both species. Results: Both investigated Livistona species are rich in polyphenolic constituents, showing a great similarity. The major flavonoid compound in both species was luteolin-6-C-arabinoside-8-C-glucoside and the major aglycone was acacetin, while the major phenolic acid in both species was ellagic acid. However there was a difference in the carbohydrate content between the two species, the main sugars, before hydrolysis, in L. decipiens were arabinose, mannose and sucrose, while the main sugars in L. australis were glucose, fructose and maltose. However, stachyose was the major polysaccharide obtained after partial acid hydrolysis. L. australis showed protective activity against ulcerative colitis in lower dose 500 mg/kg when compared to L. decipiens that only showed effectiveness at a doubled dose 1000 mg/kg. Conclusion: Both Livistona species have potential medicinal value being rich in polyphenolic and polysaccharide contents and having protective activity against ulcerative colitis.