The purpose of this study is to investigate information on performance of ventilation in high-tech microelectronics cleanrooms using computational fluid dynamics (CFD). One liquid crystal display (LCD) company was examined for evaluating the relationship between workplace concentration and ventilation rate efficiency by using CFD software, Airpak 3.0v. Acetone concentration in cleanroom for final packing process, which is inspected LCD was 40.1 ppm (GSD 1.91) (n = 55) as geometric mean, ranged 7.8~128.7 ppm and weakly correlated with ventilation rate efficiency (R2 = 0.37, p < 0.01). Resulting from computational fluid dynamics (CFD), acetone concentration can be reduced 62% when install booth type local exhaust system, the most efficient way among 10 other different ventilation methods like increasing volume of general ventilation, changing the location of workers, supply or exhaust diffusers and install downstream type local exhaust system, etc. We found that volitile organic compounds in cleanroom can be a matter of adverse health effects and the concentration was correlated with ventilation rate efficiency. The most optimized plan to control the contaminants in solvent cleaning work in cleanroom was booth type local exhaust system. Keywords : Ventilation, Cleanroom, Computational fluid dynamics, Microelectronics