The blood test unit at Chase Farm Hospital has been relocated within the site.
Patients would previously had to queue outside before giving blood, but the centre has been moved and is now sited next to the urgent care centre.
Royal Free London NHS Trust took over Chase Farm Hospital and Barnet hospital in July, and chief executive David Sloman promised to move the blood test unit before the winter.
Fiona Jackson, director of Chase Farm Hospital, said: “The new location is much more convenient for patients.
"There is plenty of room inside so they no longer have to wait in the cold and the rain. We hope this will make a big difference to the patients at Chase Farm Hospital.”
Mr Sloman added: “I am pleased we have been able to find a more suitable location for our blood test unit. Something like this can make a huge difference to patients. This is part of our commitment to improve facilities at Chase Farm and to modernise the hospital.”
A planning application is expected to be submitted to Enfield Council in November and work on the redevelopment is due to begin next year.
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