A rapid, sensitive indirect immunofluorescence assay based on the use of acetone-fixed virus producing MOLT T4/LAV cells was adapted for the detection of anti-HIV antibodies. At the same time, 1486 serum samples, collected by the AIDS Surveillance and Study Centre of Modena, were tested by ELISA and IFA: the percentage of agreement of both assays was of 99.66%. Such datum suggested that IFA could be used as a serological assay for screening and confirmatory purposes.