The UK's leading children's hospital is owed £30m for treating overseas patients, figures show.
Great Ormond Street Hospital for Children was owed £30m for the 12 months to August, according to board papers.
Income from this sort of work was £55.2m.
A report to the trust's most recent board meeting said a large proportion of the debt was over 200 days old.
It said: "Overall, the [international private patient] debt remains high and expedient recovery of monies owing remains a key objective for the trust."
The trust confirmed this financial year it has taken legal action to recover a £1.5m debt, the Health Service Journal (HSJ) reported.
Over the summer, the trust was paid £1.5m it was owed by the Saudi Health Office and £2.7m owed by the Kuwaiti Health Office.