Only around half offer the facility to order repeat prescriptions online, and under two-fifths advertise extended opening hours online, a Reform Scotland survey of 994 GP surgeries found.
Most GP surgeries are private contractors but the statistics are even worse among Scotland's 42 practices directly funded by the NHS, Reform said.
Less than one-third have a website, and none offer online appointment bookings.
The Royal College of General Practitioners and the Scottish Government has previously advised that improvements in access could be made by adopting digital innovations.
Research highlighted a wide variation in availability of appointments, with some practices only offering appointments on the day while others allowed appointments to be booked six weeks in advance.
Reform Scotland's director Geoff Mawdsley said: "This report is not about the medical care provided by individual doctors or GP practices, but about the practical arrangements as to how patients access their GPs, the gate-keepers to our health service, and whether we can't improve arrangements to encourage a better provision of service.
"Surveys such as the Scottish Government's health and care experience survey tend to suggest that while the public often praise the care they receive, there can be frustrations with the difficulty in accessing that care to begin with.
"Reform Scotland believes that it is simply unacceptable that there is such a wide variation in the way people can access GP services across Scotland, a variation that has nothing to do with the size or geography of the area covered by different practices. We were surprised that in 2014 just 67 per cent of GP practices have a website and only just over half allowed you to order a repeat prescription online or by email. The results are particularly disappointing considering that the Royal College of General Practitioners developed a toolkit in 2010 highlighting the usefulness of the internet.
"Reform Scotland believes that giving individuals greater choice over their GP practice would mean that people were able to easily walk away from GP practices they felt did not provide services that suited them. We don't envisage that such a policy would lead to a mass exodus of patients from GP practices, but the potential that they could would give them much greater influence over the way services developed."
Meanwhile there is to be a one-year pilot project to see if patients of GP practices in the Western Isles benefit from the clinical expertise of a pharmacist.
The £62,000 project will involve a pharmacist working with dispensing GP practices in Lewis and Harris as well as the Uists and Barra to provide care and advice to patients. There are only three community pharmacies in the Western Isles all in or near the main town of Stornoway on Lewis.