ELISA, immunodot and DNA hybridization methods have been adapted to detect African swine fever virus (ASFV), and their sensitivities were compared using virus obtained from cell cultures. About 2.3 x 10(2) 50% hemadsorbing doses (HAD50) of virus were detected with ELISA sandwich using an anti-ASFV IgG biotinylated followed by avidin-peroxidase. The immunodot technique showed similar sensitivity, detecting about 4.6 x 10(2) HAD50 of virus. ASFV-DNA was detected using radioactive DNA probes and molecular hybridization. The maximal viral detection capacity of this technique was about 1.8 x 10(3) HAD50. The antigenic and DNA detection of ASFV during the infection of animals with virulent and attenuated viruses, was also studied. For this purpose, sera and red blood cells from several infected pigs were obtained at different days post-inoculation. The virus was detected at the third day after infection by the three methods. However, ASFV-DNA detection was more efficient than antigenic detection at nine days post-inoculation, when antigen detection failed, because immunocomplexes with circulating viruses were formed in the subacute infection.