A mother spent two hours waiting with her sick baby on a hospital children's ward while the doctor they were due to see was passing in front of them on a unicycle.
After Paula Dadswell complained, she received a letter from hospital managers assuring her that in future all unicycling on the ward would be restricted to "special occasions".
Miss Dadswell, 33, had taken her six-month-old son James to South Tyneside District Hospital, South Shields, after he fell ill.
As they waited to be seen, she watched the young doctor practising his one-wheel feats up and down the corridors of Ward 12 as nurses looked on.
He eventually put down the unicycle, picked up his notes and walked over to assess James's condition. Miss Dadswell said she told him: "You must be joking."
"His face went bright red. We had been asking for someone to see James for two hours and we had even told the doctor that he probably shouldn't be cycling around in case he hurt someone," she said.
Miss Dadswell lodged a formal complaint about his behaviour with the main reception of the hospital and received a letter of apology later that week.
The trust wrote: "All staff have been informed that such activities are to be confined to specific events, eg parties, fund-raising activities etc.
"As a children's ward, we strive to combine professionalism with an air of informality and fun aimed at putting children at ease. I accept on this occasion that we did not succeed in achieving this compromise."
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Miss Dadswell said: "We asked the doctor what he thought he was playing at, and he said he had not had the unicycle very long and was trying to learn how to ride it.
"It was as if that was more important to him than his job. There were no other children for the doctor to be entertaining; he was simply messing around with the nurses."
James's father, Alan Dukes, said his son was later diagnosed with an ear infection by the family GP.