Abstract The ancient theatres present today two sides: an architectural one, as archaeological site, and an artistic one, as an entertainment place. This double cultural heritage generates conflicts in the manner of use, so in ancient theatres conservation rules sometimes collide with the intense (and often inappropriate) use during the theatrical summer season. This article presents a research conducted on the Greek theatre of Syracuse related to acoustic and lighting comfort. A parametric study through the prediction software Odeon 10.1 and Relux 2012.1 has been carried out by adding different scenic elements in the theatre to evaluate their influence on acoustic quality and solar radiation. For the acoustic part, the comparison between the conditions with and without the scenery allowed to establish guidelines for scenic design, to preserve and improve the original acoustic apparatus. The computer model was calibrated according to in situ measurements performed in non-occupied conditions. For the lighting part, the natural light analysis during the hours of daytime use of the theatre defined potential elements of discomfort for the viewers, due to glare or high contrasts of luminance between scenery and sky. Through an integrated approach of acoustic and lighting design it has been possible to solve those problems.