The number of men registering as sperm donors has risen by 6% in the year following the law removing donor anonymity, latest figures show.
Around 500 sperm donors are needed each year in the UK
Some had feared potential donors may be deterred if they could be identified.
But in the 12 months following the law change there were 265 new sperm donors registered with the Human Fertilisation and Embryology Authority.
This compares with 250 in the year before the law came into force for donors in April 2005.
And early indications are that the numbers of sperm donors are "continuing to increase all the time", according to the HFEA.
But experts said donor services remained "patchy at best".
Last September, the BBC contacted the 84 fertility clinics and one sperm bank in the UK and of the 74 that responded more than two-thirds (68%) said they were getting "no sperm" or are having "great difficulties" in getting some.
The results showed that 90% of all UK donors were in just 10 clinics.
The latest HFEA rates include UK sperm donors and imported sperm.
Shirley Harrison, chair of the HFEA, said the decision to remove anonymity for those sperm and egg donors who registered after 1 April 2005 had always been controversial.
"Many commentators continue to claim that the change in law to remove anonymity for sperm and egg donors would lead to an immediate and steep fall in the number of donors. These new figures show that the predicted drop in sperm donor numbers is a myth."
The number of sperm donors has been falling since the Nineties - when there was a peak of 459 donors.
The British Fertility Society (BFS) , the National Gamete Donation Trust (NGDT) and other organisations have been looking at ways to improve the numbers of sperm donors recruited in the UK.
Ms Harrison said: "These figures show that these efforts have been paying off."
Dr Mark Hamilton, chair of the BFS, was still concerned about the availability of sperm donation services in the UK.
He said: "The BFS is aware of several centres which have now withdrawn donor insemination services to patients, and for those who may be fortunate to be able to access treatment, costs and waiting times have greatly increased."
He said a working party convened by the BFS, with representation from providers, patients, the HFEA and the Department of Health, would be reporting shortly with an analysis of the present situation and would make recommendations on national service delivery.
NGDT chair Laura Witjens welcomed the increase but said the number of donors
were still far short of the estimated 500 donors needed to meet demand.