Anthony Neilson's revival of Peter Weiss’ play, which opened last week as part of the company's 50th anniversary season, includes scenes of nudity, torture and simulated sex acts.
Theatregoer Kate Dee, 25, from Worcester told the Daily Mail: "It was utter filth and depravity. The rape scene came just before the interval, and many people did not return for the second half ... I knew it was supposed to be edgy but it was the worst kind of filth dressed up as quality theatre."
The RSC has admitted that an average of 30 people have left the new Royal Shakespeare Theatre each night since the production began previews on 14 October.
But artistic director Michael Boyd defended the play, saying, "Marat/Sade changed the face of British theatre when it premiered in 1964. It’s a controversial play because the subjects it explores – insanity, individuality, sexuality, the abuse of power, freedom versus control – are just as sensitive today as they were in the 1960s."