Abstract: A network emulator in asynchronous transfer mode, consisting of emulating the performance of a digital network of integrated wideband services operating in asynchronous transfer mode, with no need to use said network, or else emulating intense operating conditions typical of a very loaded network on anunloaded network, having a line interface module (1), one or several central modules (2), a control module (3), and an operating module (4), having an electro-optical converter (9), a series/parallel converter in receiving, and a parallel/series converter in transmitting, as well as a network terminator (11), with asynchronous transfer mode, and a bit error rate generator, the central module (2) or modules being configured by a variable delay block (12), a cell error block (13), a cell loss block (14), an erroneous insertion block (15), and a constant delay block (16).