This paper describes the measurements and evaluation of the indoor thermal environments in a large domed stadium. This stadium was built mainly for professional baseball games, but it has a lot of other purposes. It will be used not only for many sport games but also for various entertainment events. To satisfy such purposes, various intelligent mechanical systems were equipped to control and create a suitable space and environment without consuming excessive energy. A multi-zonal air-conditioning system with an under-seat supply of conditioned air and displacement ventilation is one of these. Measurements, including temperature distribution, humidity, air flow and outdoor weather conditions, were carried out for three seasons, with each measurement period lasting for a week. In this paper, the results during the summer are discussed. The results show that the horizontal temperature distribution indicates that the air-conditioning system separates the space effectively and that each zone can run well separately. The vertical temperature distribution also indicates that the under-seat supply air-conditioning system provides air-conditioning to a limited area, or to the occupant zone only.