The Scottish Government said 400 people a week in the area were now signing up to the list, which should boost the prospects of patients who require an organ transplant.
Both NHS Lothian and the government have worked hard to increase numbers on the register.
The challenge was not persuading people of the merits of organ donation, experts said, but simply urging them to formalise that willingness.
Health Secretary Nicola Sturgeon said: "Signing up to save a life is easy, yet it's potentially one of the most generous things any of us will ever do.
"Transplants save lives and can help ensure that something good can come out of the tragedy of a loved one's death.
"Yet there are more than 600 people in Scotland waiting on a life-saving transplant and, sadly, not all of them will get an organ in time.
"That's why we have been working hard to increase the number of people on the organ donor register."