The drug metabolizer phenotype of the major P450 enzyme, CYP2D6, can be predicted by genetic analysis. The combination of full, reduced, or no function alleles, in addition to gene copy number, is used to determine ultrarapid, extensive, intermediate, or poor metabolizer status. Data from quantitative PCR (qPCR) experiments using TaqMan™ SNP Genotyping assays and TaqMan Copy Number assays can be translated to star allele diplotypes associated with metabolizer phenotypes. While qPCR can decipher most of the information necessary, phenotypes cannot be unequivocally assigned for samples that contain a CYP2D6 duplication or multiduplications and are heterozygous for alleles that are known to be duplicated and that have different functional levels. For these samples, allele-specific copy number analysis by digital PCR (dPCR) can be done in order to identify the duplicated allele. Digital PCR enables single sample analysis with high precision and sensitivity by partitioning target molecules into 20,000 individual reactions, thus elucidating the ratio of the heterozygous alleles. For the allele-specific copy number variation (ASCNV) application, TaqMan SNP assays to CYP2D6 variants that are associated with specific duplicated alleles were run in dPCR on samples of known SNP genotype and CNV status. Initial validation was conducted on Coriell cell line gDNA samples. Here we describe work done on buccal swab samples collected from two different sites. Representative samples carrying CYP2D6 duplications that were heterozygous were selected to run with ASCNV dPCR.