Health boards around the country are paying "enhanced" rates to doctors who provide the out-of-hours cover when surgeries close down for up four days at a time over Christmas and New Year.
But the Scotland Patients Association said doctors should be willing to work for less given the financial challenges currently facing the NHS.
Doctors leaders, however, defended the pay rates, saying they were justified if medics were to sacrifice time with their families.
The highest rates are being paid by NHS Lothian at 143 to 145 per hour for Christmas Day and Boxing Day and January 1 and 2. This compares to a normal average rate of 60 an hour for out-of-hours cover.
Scotland's biggest health board, NHS Greater Glasgow and Clyde, pays GPs up to 135 an hour for working Christmas Day and New Year's Day, with rates of 71 to 118 per hour for the rest of the festive public holidays. The normal rate is between 50 and 79 an hour.
With 109 GPs working in the region on Christmas Day, the total bill will be almost 100,000 for just one day's cover alone. Across Scotland, the final sum is likely to run into millions for the whole holiday period.
Margaret Watt, chair of the Scotland Patients Association, said: "That kind of money is quite obscene. But I have to think of our patients and, if it is a way of our patients being attended to over that period of time, then I suppose we have to bite the bullet although it is a very bitter bullet to swallow."
Watt said given the financial difficulties facing the NHS, doctors should be willing to accept less pay to work out-of-hours "in the interest of people's health and welfare".
But Dr John Garner, a GP in Edinburgh and former chairman of the British Medical Association (BMA) Scotland, defended the higher payments. "If you want doctors to give up their family lives over Christmas then you have to pay more than the normal rate," he said.
"They have to sacrifice home life, go out in freezing conditions and I think the money is justified."
Garner also pointed out that GPs had taken a significant pay cut to fund the out-of-hours service when they were allowed to opt out of providing cover in 2004.
Jackie Baillie, Scottish Labour health spokeswoman, said: "We do need to recognise that it is a difficult time of year, people want to be at home with their families. It does strike me however that while we would want to make enhanced payments to people working at the Christmas period they should be proportionate."
Health Secretary Nicola Sturgeon said: "Health boards are responsible for ensuring that they have appropriate clinical services in place over the festive holidays. It's important that these services are clinically effective as well as offering the best possible value for money."