As genetic technologies make the detection of genotypes associated with gene-based diseases increasingly possible, widespread genetic testing is being advocated by some. The technological capacity to detect conditions, however, is outstripping our ability to assess appropriately whether this is effective, ethical and economically feasable. When are such tests indicated? Who should pay for them? To whom should they be offered? Who should have access to the results? What are the implications for equity of access to services? What are the effects on the healthcare system?