Millions of asthma patients are not getting basic levels of care, a charity has claimed.
Not getting basic levels of care can lead to fatal consequences, Asthma UK said.
But its latest poll found that two thirds (65%) said they were not getting at least one element of basic care, as recommended by health experts, including having an inhaler technique check, an annual asthma review and having an "asthma action plan" in place.
The charity estimates that this means that 3.5 million patients are not getting the care they are entitled to.
"Only 35% of people with asthma are receiving the most basic level of asthma care, and the consequences of this lack of provision are fatal," the authors said.
The charity said that three people die from asthma every day in England and Wales and estimates suggest that two thirds of these deaths could be prevented with basic asthma care.
Meanwhile, the charity said that there was a "postcode lottery" of care for asthma patients.
Just 26% of those in Wales received every element of basic care compared to 34% in England, 43% in Scotland and 48% in Northern Ireland.
The survey of more than 7,500 asthma patients from across the UK also found that 15% claimed to be getting poor care, be it from their GP, emergency hospital care or specialist services.
Dr Samantha Walker, director of policy and research at Asthma UK said: "We are deeply concerned about this bleak picture of asthma care.
"There's a postcode lottery with millions not getting basic asthma treatment, despite the fact it is proven to save lives, and thousands saying the care they did get was poor.
"It shouldn't matter where you live - people with asthma should get a written plan to help them manage their asthma, a yearly review to check their medicine is working and help to ensure they are taking it properly.
"Healthcare professionals need to ensure they are giving patients this care and patients should proactively manage their asthma, and attend their appointments to keep asthma attacks at bay."
An NHS England spokesman said: "GPs are best placed to provide appropriate asthma treatment and we are rolling out support to help them improve the diagnosis and treatment of the condition, including the development of local hubs that will make testing more effective."
A Welsh Government spokesman added: "Improving the respiratory health of the people of Wales is a major challenge for all healthcare services. We recently launched our vision for respiratory services in Wales which we expect to improve the quality of life for many patients with acute or chronic respiratory diseases."