Abstract: A process for the production of linear fiber-forming polyesters, especially polyethylene terephthalate, wherein vaporous reaction products are separated in an improved manner by suction withdrawal from the polymerization reactor through the action of a fluid vacuum jet or aspirator which is supplied with recirculated glycol vapor as the propellant or jet fluid for the aspirator and also by further suction through the action of a recirculated glycol liquid operating a liquid circulating vacuum pump in a final separation of non-condensable gases such as nitrogen from residual condensable vapors. The process is especially useful in preventing the discharge of the vaporous by-products into the surrounding environment during the production of the polyester product.