A transport system installed in a cleanroom where clean air is caused to flow from a ceiling toward a floor. The transport system includes a vehicle (1) for transporting loads, and a guide rail (2) suspended from the ceiling to guide the vehicle (1). The vehicle has a main body (6) for running along the guide rail (2), a load supporting deck (7) disposed over the main body (6), and connecting members (8) for interconnecting the main body (6) and load supporting deck (7). The guide rail (2) is enclosed in a tubular cover (3) defining an opening ("d") extending longitudinally of the guide rail (2) for receiving the connecting members (8). The cover (3) has a substantially streamline configuration with respect to the direction of clean air flows. <IMAGE>
