The effects of the geometrical parameters of draft tubes and the clear liquid height on the average gas holdup E-G in a 0.16 m I.D. bubble column for gas dispersion into the tubes were experimentally studied in an air-tap water system. The gas holdup depended on the superficial gas velocity U-G, the kinds of gas spargers, the diameter and length of the draft tubes, clearance C-b between the lower end of the draft tube and the bottom of the bubble column, and the clear liquid height H-L. E-G increased with decreasing hole diameter of the gas sparger at a small gas velocity U-G, but did not depend on the kinds of gas spargers at a large U-G. E-G decreased with increasing clear liquid height H-L. The effect of H-L on E-G was well expressed by the modified three-region model. The experimental data of E-G were correlated.