An active chilled beam (ACB) system is known to be not only energy-efficient, but also advantageous to high indoor environment quality. For this reason, its application for indoor climate control is increasing in Europe, North America, and even Asia. The objective of this study is to evaluate the performance of the ACB system in terms of uniformity for the indoor thermal environment. To investigate the thermal uniformity of the ACB system, comparative experiments were conducted in a full-scale test bed, where conventional air distribution systems as well as the ACB system can be selectively operated. The thermal uniformity was evaluated with three performance indices: ADPI to evaluate the air diffusion performance, air velocity to evaluate the local discomfort due to cold draught, and vertical air temperature difference to evaluate temperature stratification. The result shows that the ACB system is successful in providing the acceptable thermal uniformity, even with less air flow rate than other conventional air distribution systems. (C) 2015 Elsevier B.V. All rights reserved.