For the second time, a survey conducted in parallel with the 2003 SUMER survey—and carried out in accordance with the principles of occupational questionnaire analysis by an industrial hygienist—made it possible to compare the results of the chemical exposure assessment obtained by the two methods. To do so, employees agreed to participate in this parallel survey as a secondary measure by completing an occupational questionnaire covering the same workweek as that described for the SUMER 2003 survey. Their occupational descriptions were analyzed by an occupational hygienist, who was unaware of the findings from the occupational physician, and the results of the two methods were compared. A clear improvement in the consistency of the estimates, compared to the results of the same experiment in 1994, was observed, due mainly to the quality of the guidelines provided for the assessment of chemical agents in SUMER 2003. However, for certain compounds, particularly mixtures, a dispersion in the assessments persists, which may lead to some distortions in the mapping of these exposures. (R.A.)