Scots should be able to choose their GPs from within wider catchment areas, according to a think-tank.
Reform Scotland also said all surgeries should have a website and provide clearer information for patients.
The public policy institute made a series of recommendations it said would give patients greater choice in picking a practice which provides services suited to them.
In a report, the organisation said research showed where you live will often determine whether you can attend an evening or weekend surgery, or order repeat prescriptions online. By expanding a practice's catchment area, Reform Scotland believes patients will be provided with more choice which will drive up standards.
Director Geoff Mawdsley said: "Reform Scotland believes that it is simply unacceptable that there is such a wide variation in the way people can access GP services, whilst there is little or no choice over where they can register.
"By enabling patients to move and go elsewhere if they are unhappy with the way they can access services where they are, there is greater pressure on all GP practices to improve."
The paper, Patients First: Improving access to GP practices, also recommends allowing new surgeries to open up to further increase choice and improve services. It also said it believes the ban on private sector companies opening GP practices should end.
However, doctors' leaders said they disagreed strongly with the recommendations.
Dr Alan McDevitt, chairman of the British Medical Association's Scottish general practitioners committee, said while the report had picked up on the important issue of access, he "could not disagree more" with their proposed solutions.
"What some call postcode lottery others would call local flexibility. A proportion of services provided by practices are agreed locally between the health board and individual practices according to local priorities," he said.
"In the case of extended hours, for example, what is the point of a GP spending time running a late surgery if there is no demand for it locally? We will always have to work to improve access as there is no 'perfect' solution.
"Patients across Scotland can choose from a number of local GPs, with some obvious exceptions, such as in rural areas. The idea that we should expand our practice boundaries demonstrates a clear lack of understanding of the reality of the work and structure of general practice."
A Scottish Government spokeswoman said: "While Local NHS boards are responsible for decisions on these areas, we believe the proposals are interesting and we would be keen to consider and discuss further as part of our efforts to improve access."