There are many methods of teatment of the intussusception in children including surgery barium reduction air reduction and saline enema under ultrasonographic monitoring. Among them barium reduction and air reduction have been used widely as nonsurgical method of treatment in radiologic department. During barium reduction the bottle filled with barium solution must not be elevated over a 3 feet from the operating table. In air reduction diagnostic pressure is about 60 mmHg and pressure during reduction usually is maintained between 90 mmHg and 130 mmHg. The authors have studied about pressure difference of barium solution by changing height of the bottle filled with barium solution and have compared with pressure in air reduction, The results are as follows. 1. Pressure of 20 w/v% barium solution at the 60 cm height is 44.4 mmHg and 69.6mm Hg at the 90cm height. 2. Pressure of 40w/v % barium solution at the 60 cm height is 51.4 mmHg and 80.1 mmHg at the 90 cm height. 3. Pressure of 40 w/v % barium solution at the 90cm height is much lower than the pressure maintained during air reduction and this difference in pressure may be noe of the causes of low reduction rate in barium reduction than air reduction. 4. The pressure gradient per 10 cm height is about 8.45 mmHg in 20 w/v % barium solution. about 9.21 mmHg in 30 w/v % barium solution and about 9.72 mm Hg 40 w/v % barium solution.5. Intraluminal pressure difference between the barium reduction and the air reduction is probaly one of the major causes of rapid diagnosis and high reduction rate in the air reduction.