Scores of people gathered at a city temple to bolster supplies at the blood bank.
About 150 donors visited the Gurdwara Guru Tegh Bahadur, in East Park Road, on Saturday.
The event was aimed at collecting blood from black and ethnic minority donors, as well as raising awareness about donating.
Theo Clarke, lead donor relations manager at the NHS, said: "It's vital people from all backgrounds donate blood so that patients in their communities get the life-saving transfusions they need.
"Blood has a limited shelf-life of 35 days for red blood cells and just seven days for platelets.
"Because of this, it is important that both existing and new blood donors come forward and donate regularly so we can ensure vital supplies are available for the patients that need them."
The temple is planning similar events every six months.
Amandeep Rai, 33, from Knighton, Leicester, who was at the event, said: "It was a real success, we were expecting about 50 people but we got 150.
"I don't know why Asian people in particular don't donate, maybe it's a cultural thing, but we're hoping to make these more regular and encourage more people to start giving blood."