This paper presents an ergonomic design of the display system in control rooms of four complex systems in Serbia, railway, mining, electric power, and soybean flakes production. Research of display panels analyses the visual information coding, characters' visual angles, and existing standards and recommendation in the period when this research took place. Operators' visual angles, the distance between the operator's eyes and display panels, the size of visual signs, comparative analysis of display panel and video display units used in the control room are given. The main goal of this paper is to apply the result obtained in designing a new control room in Serbia since the adequate design of display systems in control rooms has a significant impact on the efficiency and functionality of the operator's work in control centers.