Nigel Farage's right-hand was booed on BBC's Question Time for arguing that the NHS crisis is caused in part by immigration.
Ukip deputy leader Paul Nuttall, also an MEP, prompted anger after arguing immigration was fuelling demand for health services.
He said: "The bigger problem with the NHS is allowing 300,000 people coming into the country each year. You can't plan for an NHS when there are too many people in the country."
To jeers from the crowd, writer and activist Paris Lees responded: "Shame on you. We would not have an NHS without doctors coming from other countries."
It was during a wider debate on the NHS that saw the Government pilloried despite a promised extra £8 billion a year of investment.
Meanwhile, the normally supremely-relaxed Question Time presenter David Dimbleby almost lost his cool when Mr Nuttall gave a lengthy peroration on the show about Britain being controlled by Europe.
"Stop making a speech, Paul," the respected broadcaster snapped at the MEP, whose party wants Britain to leave the European Union. "I know you're used to making a speech ..."
His slapdown earned cries of "more" from the Stoke-on-Trent audience.
ALSO ON QUESTION TIME: