Three different techniques, which are tracer, drainage and weighing methods, are used to measure liquid holdup in a laboratory trickle-bed reactor operated under high pressure. The holdup measurements are compared to determine the applicability of these methods at high pressure operation. It was found that tracer and drainage techniques give comparable values for the total liquid holdup. Although several investigators recommended the weighing method over the others based on their experiments performed at atmospheric conditions, it was found that the weighing method failed to measure liquid holdup properly at high pressure operation.