[Show abstract][Hide abstract] ABSTRACT: An accurate and reproducible CD4 count is a fundamental clinical tool for monitoring and treating human immunodeficiency virus infection and its complications. Two methods exist for calculating absolute CD4 counts: dual-platform technology (DPT) and single-platform technology (SPT). Numerous studies have documented the unacceptably wide range of variation in absolute CD4 counts between laboratories. SPT was introduced in 1996 to reduce the interlaboratory variation in absolute CD4 counts. The aim of this study was to compare DPT with the BD Biosciences Trucount method (an SPT method). Both the percentages of CD4 (r = 0.986; P = 0.0541) and the absolute CD4 counts (r = 0.960; P = 0.0001) had very good correlation between the two methods. However, poor correlation was observed for the CD8(+) RO(-) (r = 0.314; P = 0.0002), CD8(+) DR(+) (r = 0.666; P = 0.0138), CD3(+) CD38(+) (r = 0.8000; P = 0.0004), CD3(+) CD25(+) (r = 0.464; P = 0.0082), and CD4(+) CD38(+) (r = 0.357; P = 0.0127) measurements.