The NHS Blood and Transplant service is making a special appeal to O negative and B negative blood donors to make a donation at their nearest blood bank.
The service said that Wimbledon mania and the arrival of summer have affected the numbers of people coming forward to donate.
Donations across all blood groups fell 11 per cent during the last two weeks, compared to the same fortnight last year.
And on Sunday 7th July, the day of the Wimbledon final, donations dropped by 31 per cent.
“Summer finally arrived, temperatures and hopes rose during Wimbledon and blood donations fell,” said Jon Latham, assistant director for marketing at NHS Blood and Transplant.
“Stocks of blood for vulnerable blood groups – O Rh negative and B Rh negative - are lower than we would like them to be and I’m asking blood donors with those two groups in particular, to walk in and donate now.”
“By doing so you can help us replenish vital stocks and ensure that we can continue to meet the needs of patients.”
Donors are urged to make an appointment to donate at www.blood.co.uk or call 0300 123 23 23