The former cabinet right-winger was featured across four pages of the Mail on Sunday describing how he spent three days working, unpaid, as a porter in St Thomas' Hospital, London.
Mr Portillo said that he took the job as he thought it would offer "a good perspective to glimpse the real life of a hospital". However, Labour dismissed it as a "transparent stunt", claiming it was part of his long- term campaign to oust William Hague as Tory leader.
"Coming at a time when focus groups are dubbing William Hague a `nerd', Mr Portillo's timing couldn't be better," said the Cabinet Office minister, Ian McCartney. "Michael Portillo's plot to return to Parliament and snatch the leadership is now in top gear."
In the article, Mr Portillo recounted his experiences, from delivering bodies to the mortuary to comforting, in her own language, a Spanish woman about to give birth.
And he lavished praise on hard-pressed NHS staff who kept up their good humour despite the often difficult conditions in which they had to work. "It calls to my mind the famous British wartime spirit," he wrote. "The NHS was conceived during the Second World War and it seems to have been preserved in aspic."
He likened the scene in the casualty unit on a Friday night to something out of the Crimean War, with a corridor full of men with "their heads bandaged, their faces encrusted with dried blood and their clothing stained red".
Mr Portillo, who has been working assiduously to present a "softer" image since losing his seat at the 1997 general election, also backed calls for more spending on the NHS.He recorded staff complaints about one of the Tories' keynote policies, contracting out services such as portering and catering, and their relief that they are now back "in house".