A majority of towns in Asia Minor have an open-air theatres built in theancient Greek and Roman periods for performances and ceremonies. Thenumbers of these theatres are more than 50 and some of them are still ingood condition for present use. However, today, even the large cities inTurkey do not have such theatres with a large audience capacity. In recentyears, there Is a tendency to build open-air theatres with small capacityespecially in the holiday villages in the south and west of Turkey. Suchtehatres have the opportunity of use for, at least eight months because of thesuitable climatic conditions of the region. In respect to town needs andtourism purposes these ancient theatres could be restored. In order to avoidpossible acoustical defects that might be caused in restoration, reasons ofthe good acoustics should be known and the original form should be protected.In this study acoustical properties of the theatre of Aspendos have beenexamined by using geometrical room acoustics approach. Sound reflectionsfrom orchestra surface and stage wall have been simulated on computer. Animpulsive sound source has been used to record sound at several locations inthe theatre by an instrumentation tape recorder. These recordings have beenlater analyzed on computer and compared to the simulation results.Reflection patterns obtained from analytical and experimental studies arediscussed and evaluated. Locations where echoes are present are alsodetermined.