The effect of various precooking treatments on the elimination of flatulence factors in 3 mung bean [Vigna radiata] varieties (Kawmi 1, M53 and 2719) was evaluated by determining their oligosaccharide contents. The mung bean seeds were subjected to various treatments commonly employed to eliminate the flatulence factors in legumes: ordinary cooking; soaking in tap water; cooking of soaked seeds; autoclaving or microwaving of soaked seeds; and cooking of soaked and autoclaved or microwaved seeds. The contents of oligosaccharides in processed and unprocessed mung beans were extracted with 80% ethanol and then qualified and quantified using high performance liquid chromatography. The contents of total soluble sugar, reducing sugars, nonreducing sugars and total carbohydrates in the raw mung bean varieties were 9.11-9.75, 1.55-1.90, 7.30-8.20 and 56.88-58.01%, respectively. All varieties contained more verbascose than stachyose or raffinose. The contents of raffinose, stachyose and verbascose decreased in all treatments. Soaking the seeds in water for 3 h decreased the quantity of these oligosaccharides, and a greater decrease was observed when the seeds were soaked for 6 h in all varieties. Autoclaving and microwaving of soaked seeds further decreased the contents of these oligosaccharides. Soaking for 6 h followed by autoclaving or microwaving and cooking significantly reduced the raffinose, stachyose and verbascose contents by 75-86, 68-83 and 71-78%, respectively. It is concluded that substantial amounts of flatulence factors can be eliminated by common processing methods.