We have used the polymerase chain reaction (PCR) to amplify CP 115 and CP 47 encoding sequences from human lens cDNA samples. DNA sequence and northern blot analysis were used to confirm human origin. From the determined cDNA sequences, human-specific oligonucleotides were synthesized and assessed for the ability to amplify human genomic DNA. After empirically selecting a primer pair for each gene able to amplify human genomic DNA, and optimizing PCR conditions for human specificity, we used the PCR to screen a panel of mouse/human somatic cell hybrid DNA samples. Amplification of CP 115 or CP 47 sequences in each of the somatic cell hybrid samples was correlated with the presence/absence of human genomic DNA sequences encoding the respective gene sequences. From our results, we conclude that the gene for human CP 115 resides on chromosome 20 and the gene for human CP 47 on chromosome 3. Further mapping using somatic cell lines carrying derivatives of human chromosome 3 localize the gene for CP 47 to 3q21–25. We propose LIFL-H (Lens Intermediate Filament Like-Heavy) for CP 115 and LIFL-L (Lens Intermediate Filament Like-Light) for CP 47 as the gene symbols for these loci.