Micro- and nanotechnology is used today as a base for a whole range of modern biomedical assays. Prime examples are next generation sequencing and single cell sample preparation. Micro technology is also used extensively to mimic physiological relationships of cell organisation (organ-on-a-chip) as well as cellular based high throughput screening. Micro and nanotechnology enables miniaturisation, precise spatial control, convenient rapid self assembly of samples, and not the least automation. However, these benefits come at price of other regimes for molecular mass transport, other materials used and practical issues to use rather complex devices. With examples of my own research regarding single molecule counting, organ modelling and high throughput technologies for drug development and diagnostics, I will highlight advantages and disadvantages of employing micro and nanotechnologies in biomedical assays. While these novel technologies are here to stay, they are far from the well known polystyrene cell culture dish, the Eppendorff tube, and the pipette which the vast majority of biomedical research is based on. Therefore, employing these new methods have far ranging implications in assay design but also to what extent data gathered with these new methods can be compared to the current literature.