An inter-laboratory study was organised for the monitoring of emerging aquatic pollutants (pharmaceuticals, pesticides, steroids, brominated diphenyl ethers and others) using passive samplers. Thirty laboratories participated in the sampler comparison exercise. Various samplers designs were exposed at a single sampling site to treated waste water. The organisers deployed in parallel multiple samplers of a single type, which were distributed for evaluation of the contribution of the different analytical procedures to the data variability. Between laboratory variation of results from passive samplers was about factor 5 larger than within laboratory variability. Similar results obtained for different passive samplers analysed by individual laboratories and also low within laboratory variability indicate that the passive sampling process is causing less variability than the analysis. Concentrations in composite water samples were within the range obtained by passive samplers. In future a significant improvement of analytical precision and calibration of adsorption based passive samplers is needed.