Ancient Sikyona was re-founded in 303 BC. after the conquest by Demetrius the Besieger. The ancient theater is estimated to have been built during the early Hellenistic era (323-275) BC. Construction stages include elements from both the Hellenistic and Roman periods. The excavation showed that before the last century of the Roman era it must have been abandoned, as burials were found in the N.E. passing. Both the ancient theater and the wider archaeological site have been systematically excavated since 1886. After the end of the excavation work in the 1950s, it began to be used again for performances, but it stopped in 2000 by a decision of the Ministry of Culture due to the inappropriateness of the space. The present study mainly concerns the restoration of the lower cavity (orchestra, euripus, presidium, pews, ascending steps) up to the first diazomal corridor and the analymmatic walls. The archival research, the detailed mapping and the analysis of the individual elements, both of the ancient theater of Sikyona and others, led to a representation of its possible form. In the context of the needs of the organization of the archaeological site to be visited and the provision for the functional reuse of the ancient theater, an initial general layout plan was implemented (market-theatre-stadium connection, demarcation of the archaeological site, accessibility, public service infrastructure) which will be studied more thoroughly in the next stage.