The Minister for Health's car was pelted with eggs and cheese by protesters as she arrived at Nenagh General Hospital for an official function.
About 30 protesters, who claim Mary Harney has presided over a downgrading of services in Nenagh in recent years, held placards and shouted slogans at the Minister as her car was driven through the hospital gates.
A small number of eggs were thrown at the car and one of them splattered an RTÉ journalist who was present to report on the official opening of a new endoscopy unit at Nenagh General Hospital.
Protesters shouted "bloody Mary" and "you've got blood on your hands" as the Minister got out of her car at the hospital's front door.
Speaking after the protest, Ms Harney said that the range of procedures carried out in Nenagh was expanding and the hospital was on course to meet new quality standards coming into force in 2012.
"I would say to those that are outside the gates to come and talk to the people inside, who are working here every day, providing high-quality services ," she said, adding that they should not be "negative" about change.
"Change is something we all have to continue to embrace, whether it's in healthcare or other aspects of our lives in order to deliver a higher-quality service."
She said she "wasn't aware" of what had been thrown at her ministerial car. "I don't get upset, no. I've had other things thrown at me that were probably worse," Ms Harney said in reference to a recent incident in Dublin in which she had paint thrown on her.
The Minister's visit to Nenagh was the subject of controversy from the time it was announced, with hospital campaigners complaining that she had already downgraded services in the hospital during her term in the Department of Health.
It was "a great pity" that people don't use our democracy to engage in debate, she said. "Politics is about choices, it's about arguing and debate. It's not about engaging in public disorder offences or indulging in activity of that kind.”