She was a frequent visitor to prisons to protect prisoners from warder brutality, and campaigned for improved prison conditions. She visited Nelson Mandela on numerous occasions while he was in prison and made representations to the authorities to improve his conditions and those of other prisoners on Robben Island. In his autobiography, Long Walk to Freedom, Mandela wrote: “It was an odd and wonderful sight to see this courageous woman peering into our cells and strolling around our courtyard. She was the first and only woman ever to grace our cells". Many of the prisoners, including Neville Alexander and Mandela himself, attributed improvements to their conditions, in part, to her visits: In his autobiography, Mandela attributes the removal of the sadistic warder Van Rensberg (aka "Suitcase") to Suzman's visit and her subsequent representations to the authorities and in Parliament.