The number of people waiting for a lung transplant has gone up by 46% over the past five years, according to official figures.
NHS Blood and Transplant (NHSBT) said the challenge of matching lungs of the right size and a rising number of ageing donors are possible factors.
It called on people to talk about organ donation, because lung transplants are the only hope for those on the list.
The overall waiting list for organs has come down over the same period.
There are now 354 people waiting for a new lung in the UK, compared to 242 in 2012-13 - Laura Beattie from Greater Manchester is one of them.
'I get breathless even getting dressed'
Laura, 29, from Stretford, has cystic fibrosis and was added to the transplant waiting list just over a month ago.
Her lung function has declined over the last couple of years, and is now at around 24%.
"I've known for more than 20 years that I would need a transplant one day but I was still terrified to be told I was going on the list because it made it real," said Laura.
"But I know it's the right thing to do. I get breathless even turning over in bed or getting dressed."
Laura now uses oxygen every day and also a wheelchair when she goes out for more than a few hours.
She also requires non-invasive ventilation overnight.
Despite this, she has co-founded a fashion business with her sister.
She said: "I could be waiting a short time or a long time, I don't know. I just try and get on with my life.
"I really hope more people support and really consider donation because a transplant is my only option now and donation can save so many lives."
Lungs and hearts are both delicate organs, which makes successful donation and transplantation more problematic, particularly when donors are mostly aged over 50 and are more likely to have existing health problems.
The waiting list for hearts is the only organ-specific waiting list that has also risen.
In contrast, there are currently 6,013 people on the overall waiting list for an organ - a 17% decline over the same period, from 7,335.
NHSBT said the causes of the rise in the lung transplant waiting list were being investigated and an increased number of referrals for a transplant was a potential factor.
But family refusal remained the biggest barrier to all types of organ donation and transplantation, it said.
'Opportunities are lost'
John Forsythe, associate medical director for organ donation and transplantation at NHSBT, said 65 people died on the lung transplant waiting list last year.
"Many of those lives could have been saved or transformed had more families said yes to donation," he said.
"Sadly, many donation opportunities are lost every year because families don't know if their loved one wanted to be a donor or not. We urgently need people to tell their families they want to donate."
A new opt-out system for organ donation is planned in England by 2020, where adults will be presumed to be organ donors unless they specifically record their decision not to be.
A similar system is in place in Wales. Scotland plans to introduce an opt-out system, and Northern Ireland has also expressed an interest.