Diffusive monitors have been used for workplace air monitoring for many years, and in many cases have been found to be valid and cost-effective alternatives to conventional pumped or ‘active’ Samplers. The state of the art of diffusive sampling is reviewed briefly, with particular reference to workplace air monitoring, and the particular advantages and disadvantages of tube-type samplers are discussed. A particular problem that is addressed is the small amount of validation data available in the literature for tube-type thermal desorption diffusive samplers. An alternative source of reliable sampling rates is suggested, based on results obtained in a series of BCR-sponsored intercomparisons on sampling.