Officials say 130,000 blood donors are needed for this year's "give love, give blood" campaign, which started Monday and runs for two weeks. Last year, only 57,000 people gave blood to the state blood transfusion service.
Health Minister Henry Madzorera said Monday that many Zimbabweans are "scared of the needle" and believe there are enough donors already. Some are also afraid to learn their HIV status - official figures put Zimbabwe's HIV infection rate at about 13 percent.
The national campaign is supported by the U.S. Centers for Diseases Control and Prevention and seeks more adult donors, and U.S. funding was used to better screen donated blood.
Most blood supplies - over 70 percent - come from schoolchildren. Adults receive 80 percent of those donations.
Madzorera urged Zimbabwean adults to do some "soul searching" and contribute to the blood bank.
Deputy U.S. ambassador David W. Abell said the campaign aimed to provide blood at affordable prices after years of shortages.
A unit of blood costs $65 in government hospitals - too high for many Zimbabweans who live on a daily income of about $1.
The nation has suffered acute shortage of medical supplies in a decade of political and economic turmoil that collapsed main health services and public utilities.