More than 200,000 patients in the area covered by Cambridgeshire and Peterborough Clinical Commissioning Group have no access to the extended hours for GP appointments, according to NHS figures.
The extended hours being rolled out across England allow patients to book an appointment on Saturday, Sunday, or on weekdays before 8am and after 6.30pm.
In Cambridgeshire and Peterborough CCG, 22% of those registered with a GP, that's 215,127 people, have no access to extended hours appointments.
The data was gathered by the NHS from 96% of GP practices in England.
Of the 102 practices that provided data in the area, 19 offer appointments at all these times and 54 do so for one or more of the periods.
The Government says that everyone should have "more convenient access to GP services, including appointments at evening and weekends."
It has set a target date of October 1st for all patients to have access to extended hours.
Dr Richard Vautrey, BMA GP committee chair, said: "While schemes like this are rolled out and are successful in providing the services they are commissioned to do, we still believe the money invested in such programmes would be better spent improving core GP services.
"We know that patients are frustrated with being unable to get timely appointments during regular working hours, owing to increased demand and unmanageable GP workloads, and therefore it is these services that should be a priority for proper funding."
There are 7,153 GP practices in England. Currently, just over 6,000 of them offer some access to appointments on Saturdays, Sundays and during extended weekday hours.
The best record is in Herefordshire, and Rushcliffe in Nottinghamshire where all patients can make appointments in extended hours seven days a week. The poorest record is in South Sefton on Merseyside, where no patients have access to extended hours every day but 37% do receive some extended hours service.
In most instances, practices get together to form hubs or federations that provide the service, so patients may not see their usual doctor.
The most common day for extended hours to be offered in Cambridgeshire and Peterborough CCG is Friday. The least common day is Sunday.