The effect of pipe diameter on liquid loading initiation has been experimentally investigated using 2-in and 4-in pipe diameters. Two-phase flow parameters such as pressure gradient and liquid holdup were measured. Flow characteristics were determined by visual observation using a high speed video camera. Critical gas flow rate for liquid loading initiation has been identified and comparison between the two pipe diameters is presented. The critical superficial gas velocity corresponding to the minimum pressure gradient is larger for the smallest diameter. When the comparison is carried out in terms of mass flow rates, critical flow rate for liquid loading in 2-in pipe is smaller than that in 4-in. pipe. This supports the use of velocity strings to extend the production life of the gas well. Additionally, comparison of the data with available mechanistic models prediction shows significant discrepancies. Possible reasons for these discrepancies are presented.