The CaTCh FISH Chip is a magnetic micropore chip for rapid (<1 hour) unbiased circulating cell isolation and in situ RNA analysis. The chip was able to isolate rare circulating tumor cells from whole blood of a pancreatic cancer mouse model and from patients with advanced pancreatic cancer. The chip works by first removing white blood cells using an innovative high throughput magnetic micropore filter, then removing red blood cells and platelets using size exclusion. The remaining cell population is enriched for circulating tumor cells and can be immediately RNA-profiled using fluorescent in situ hybrization (FISH) against selected markers. As a cell sorting tool, CaTCh FISH achieved LOD ~1 cell per mL blood compared to conventional cytometry with LOD of ~100 cell per mL whole blood, and can handle large volumes (>10 mL). Captured cells can be directly imaged on the chip with a 100� objective. Though originally described as a diagnostic device for circulating tumor cells, the chip can be adapted for other cell types.