A staff member at Harefield Hospital has been suspended after a formal complaint was made about their behaviour.
The leading heart transplant hospital, which is celebrating its centenary this year, also said an investigation is under way.
A spokesman for Royal Brompton and Harefield NHS Foundation Trust, which runs the Hillingdon-based hospital, said: “We can confirm that a member of staff at Harefield Hospital has made a formal complaint about a colleague and that, in line with trust policy, an immediate investigation was launched and is still under way.
“The member of staff against whom the complaint was made has been excluded from work until the investigation has been completed. We do not feel it is appropriate to comment further at this stage.”