Dr James Logan, who appears on Channel Four show Embarrassing Bodies, said staff at Edinburgh Royal Infirmary were extremely rude to his family and should be ashamed of the service they provide.
In a series of postings on Twitter, Dr Logan, who is a tropical disease specialist on the show, said he was shocked by the lack of communication between staff in the stroke unit.
He said: "I'm not having a go at all NHS staff, but there is no excuse for the level of service in this particular unit. Christmas or otherwise."
Dr Logan, who is from North Berwick, visited the hospital after his grandmother suffered a stroke a couple of days before Christmas.
On December 28 he tweeted from the hospital: "As much as I think the NHS is an amazing service to have access to, some of the staff need retrained in bedside manner.
"Genuinely disgusted by attitude and the way family are spoken to and treated by nurses and drs in stroke unit at Royal Infirmary."
It is understood Dr Logan has since submitted a letter of complaint to NHS Lothian health board.
Stuart Wilson, director of communications and public affairs, said: "NHS Lothian takes all complaints very seriously and the information gathered is used constructively to improve our services."