Summary An experimental study of two-phase flow was conducted to investigate liquid holdup in wet-gas pipelines. The liquid-holdup data were obtained by passing spheres through a 1,333-ft [406.3-m] -long, 3.068-in. [77.93-mm] -ID horizontal pipe and measuring the liquid volumes removed. Three different two-phase mixtures were used. The holdup data were compared with predicted holdup values and were used to evaluate a mechanistic model for stratified flow. None of the methods could accurately predict liquid holdup in this low-holdup region. Two new empirical liquid-holdup correlations for horizontal flow were proposed. The first is strictly for wet-gas pipelines (0<yL <0.35); the second is for any horizontal pipeline (0< yL<1.0).