Micro Total Analysis Systems(µTAS) offer the potential to vastly improve detection of early stage cancer by doing so at a molecular level, rather than waiting for the disease to manifest into detectable tumours. They also offer much greater through-put than current laboratory based techniques.In this paper an overview is given on the development of a fluid based micro-Total Analysis System (µTAS) for genetic based detection and monitoring of cancer.The novelty of the system being developed is that micro-fluidic reactors are suspended in fluid streams in a macro-scale device.High throughput is achieved by serial and parallel lines of micro-reactors.The approach overcomes the significant engineering challenge faced in attempting to interface the macro and micro worlds. Because the reactors are enveloped in a fluid medium, contamination of the device and the associated risk of false positives are minimized.The paper gives an overview on micro-reactor droplet dispension, sample preparation using centrifuging, micro-bubble mixing, DNA amplification in a fluid based PCR system and detection using optical techniques.