The hepatitis C virus antibody statuses of only 11 (21.5%) of 51 initially reactive samples from volunteer blood donors could be confirmed by using additional screening and confirmatory assays; 23 (45%) were negative by all subsequent assays. Seventeen samples (33.3%) gave variable results in the different assays. The core and NS5 antigens were most immunogenic. An algorithm for serological screening of volunteer blood donors in blood banks of developing countries is suggested.