A concise review of the gas-liquid distributors used in trickle-bed reactors (TBRs) is presented. The following topics are considered: distributors in a large-scale reactor, quench box/redistributor, inert particle layer, application of fluid flow modeling (CFD) in distributor studies, and distributors used in a laboratory-scale reactor. Mainly four types of distributors used in a large-scale reactor (e.g., perforated plate, multiport chimney, bubble cap, and gas-lift distributors) are described along with their advantages and disadvantages. Effects of Zn various types of weep hole, such as inverted V notch and rectangular slot at the distributor tube wall and fluid distributing device at downcomer outlet, are discussed. Sizing methodology of multiport downcomer in chimney type distributors is presented. The performance of a gas-lift distributor is found to be more promising compared to other distributors. It provides intimate mixing of vapor and liquid, is less vulnerable to fouling, is insensitive to tray levelness, and distributes liquid uniformly at a large turndown ratio. This is also reflected in the increasing use of gas-lift distributors with increasingly stringent product specifications. This review presents all the information available in the literature to the best of the author's knowledge and focuses the attention on enhancing the further understanding of internals toward uniform distribution of liquid in TBRs. It also focuses the future directions of work in designing of gas-liquid distributors to further facilitate the understanding of the design of TBRs to meet the challenges of the stringent sulfur specification in transportation fuel (10 ppmw in EURO V by 2009).