A new latex agglutination (LA) test (VZVscan; Becton Dickinson, Cockeysville, Md.) was compared with an enzyme-linked immunosorbent assay (ELISA) (Varicella STAT; Whittaker Bioproducts, Walkersville, Md.) for detection of varicella-zoster virus (VZV) antibody. Of 165 samples tested, 126 (76%) were positive by LA, 123 (73%) were positive by ELISA, and 35 (21%) were negative by both methods. Six samples (4%) were LA positive and ELISA negative or equivocal; three samples (2%) were ELISA positive and LA negative. However, LA failed to detect seroconversions in four adults with varicella in samples obtained 14 to 17 days after the onset of rash. These same samples had ELISA values in the high-positive range. In addition, the recommended LA screening dilution (1:2) is not supported by published data and should be changed.