Abstract: A disposable assay device for assaying a sample has a body (10) including a reaction chamber (12) which contains or is adapted to receive an assay reagent sensitive to a component (e.g. nicotine metabolite) being assayed for in the sample. A sample collector/dispenser (20) has a sample collecting chamber (22) closed by an elastic membrane (24) and a downwardly projecting sampling and piercing tube (28), to enable a predetermined quantity of sample to be dispensed into the reaction chamber (12). The body (10) and the collector/dispenser (20) are non-detachably engageable together by engagement of rib (34) on collector/dispenser (20) with lip (18) on the body (10). A seal (32) seals the assembly to prevent leakage of the contents after use.