We classified the genotype of neutrophil Fc gamma receptor III (FcRIII) (CD16) with a new method. Genomic DNA from mononuclear cells of 39 unrelated healthy donors (13 NA1/NA1, 13 NA2/NA2, and 13 NA1/NA2 typed serologically) were subjected to polymerase chain reaction (PCR) to amplify the polymorphic third exon of the FcRIII genes. The PCR products were heat denatured, electrophoresed, and visualized by silver staining. Allelic differences were detected by distinctive electrophoretic patterns of each single strand, depending on their sequence specific conformations (single-strand conformation polymorphism [SSCP]). The genotypes of neutrophil FcRIII determined by this method were consistent with the phenotypes of NA antigens determined by serologic examinations. These results indicate that the PCR-SSCP system is a very useful tool for genotyping of the neutrophil FcRIII.