Circulating tumor cells (CTCs) hold promise for studying advanced prostate cancer. A functional collagen adhesion matrix (CAM) assay was used to enrich CTCs from prostate cancer patients' blood. CAM ingestion and epithelial immuno-staining identified CTCs, which were genotyped using oligonucleotide array comparative genomic hybridization. The highest CTC counts were observed in men with metastatic castration resistant prostate cancer (CRPC) compared to castration sensitive prostate cancer. Copy number profiles for CRPC CTCs were similar to paired solid tumor DNA, and distinct from corresponding DNA from the residual CAM-depleted blood. CAM CTC enrichment may allow cellular and genetic analyses in prostate cancer.