The Rhesus (Rh) blood group is the most polymorphic blood group system. Serological analyses revealed that only 0.1% to 0.4% of the Chinese population exhibited a D-negative phenotype. In contrast to D-negative Caucasian persons, who are mostly associated with a deletion of RHD between the upstream and downstream Rhesus boxes, approximately 30% of apparently D-negative Chinese were actually DEL, potentially harboring a grossly intact RHD gene. The authors' previous detection of the RHD 1227A allele in all DEL samples prompted the conclusion that the RHD 1227A gene is highly prevalent in DEL populations of Chinese ethnicity, which indicates that it may be a marker for the rapid detection of DEL. Currently, random surveys for RHD 1227 A allele and for hybrid Rhesus box were conducted among 399 Han Chinese in Taiwan. The estimated frequencies of RHD 1227G/G, RHD 1227A/G, RHD A/A, RHD 1227G/-, RHD 1227A/-, and RHD-/- were 0.89054, 0.0118, 0.00016, 0.0414, 0.00055, and 0.00192, respectively. These results were consistent with the prevalence of D-negative and DEL in persons of Chinese ethnicity. The authors conclude that detection of RHD 1227A and hybrid Rhesus box alleles is predictive of Rh phenotypes in the Chinese population.