The number of people agreeing to donate their organs after death is growing, but at a slower rate than the number of patients who need them, a report warns.
The first year of a concerted effort to boost UK donation rates did see the number of transplants rise as more co-ordinated services were implemented.
But the Organ Donation Taskforce notes the waiting list continues to grow.
The BMA doctors' union said it was time to seriously debate presumed consent, in which everyone is seen as a donor.
The number of people volunteering to join the register has grown by 6.5% in the last year, hitting the 16m mark for the first time, but this still accounts for only about a quarter of the population.
The taskforce is working to implement a series of recommendations to ensure that suitable organs are retrieved from those willing to donate as part of a drive to improve the UK's donation rate, which lags behind much of Europe.
More lives saved
Only about a third of potential donors in fact become donors, with relatives' refusal being a key obstacle.
In the last year, an extra 100 donor transplant co-ordinators have been appointed across the country, and new systems introduced to ensure potential donors are identified and relatives approached as death becomes the likely outcome.
The number of deceased donors increased by 11% this year, leading to an extra 174 extra transplants. Living donations also rose at a similar rate, with 104 extra transplants - primarily kidneys.
The government wants to see 25 million people on the Organ Donor Register by 2013, and the number of donations to have increased by 50%. In England, a major public awareness campaign aimed at boosting the numbers on the register is about to begin.
A system of presumed consent, in operation in many of the countries with the highest donation rates, was rejected last year by the Organ Donation Taskforce in favour of these better co-ordinated efforts to retrieve organs.
Better care, fewer organs
But demand continues to grow.
One of the obstacles in improving access to high quality organs is a reduction in the number of road accidents, which often involve the otherwise fit and healthy, combined with improved care of the critically ill - meaning more survive.
There are at present nearly 10,000 people needing an organ, a figure that is rising by about 8% each year.
One of the key factors behind this increase is the increasing incidence of kidney failure in the UK - particularly in the over-50s and black and ethnic minority communities.
Of those on the list 1,000 will die while waiting, or are removed because they have become too ill to undergo a transplant.
While welcoming the increase in the number of people signing up to be donors, the British Medical Association said "there was still much to be done".
"We very much hope the 50% increase in donation rates, predicted by the Organ Donation Taskforce, will be achieved in the next five years," said Dr Tony Calland, head of the union's ethics committee.
"But there will still be a shortage of donors and people will still be dying waiting for an organ. Now is the time to have a serious debate about changing to a system of presumed consent (opt-out) for organ donation.
"In our view having a well organised and funded infrastructure, combined with a system of presumed consent, is still the best way forward."
Betty McBride of British Heart Foundation said transplants were the best long term option for the critically ill.
"These figures are good news for patients, who could receive the transplant they so desperately need to save their life.
"However, the single most important step that could be made towards improving the availability of donor organs would be to introduce a presumed consent system. We believe that such a system with an opt-out opportunity should underpin organ donation in the UK."