Abstract: Background and Objective: Most of the studies carried out with leaves, barks and stems of Cassia species. So, the objective of this study was to characterize the chemical constituents of flowers of Cassia alata, Cassia auriculata, Cassia fistula and Cassia occidentalis by using gas chromatography-mass spectrometry (GC-MS). Materials and Methods: The GC-MS analysis of flower extracts was performed using a GC and MS JEOL GC mate system and Interpretation on mass spectrum GC-MS was conducted using the database of National Institute Standard and Technology (NIST). Results: From the GCMS study, 12 phytocompounds were identified from C. alata flowers, 9 compounds from C. auriculata flowers, 12 compounds from C. fistula flowers and 13 phytocompounds identified from the C. occidentalis flower extract. A compound namely, Pregna-5, 8, 16-triene-3à-ol-20-one acetate (its chemical name is 16-Dehydropregnenolone acetate) found first time in C. occidentalis flowers, which is used in the preparation of anti-cancer agents. Conclusion: From the results obtained it was concluded that Cassia sp. contain various phytochemicals, justifying their use for various human ailments.