Occupational hygienists or safety engineers perform exposure assessments, mostly with very little participation by the workers. The objective of our study is to involve the workers themselves in the assessment and measurement procedure, the self-assessment method (SAE). A pilot study has been carried out involving tank truck drivers at a company transporting gasoline. The drivers were supposed to decide themselves when, and how often, they wanted to measure benzene exposure by using diffusive samplers that were then sent by mail for analysis. After every measurement they received their own results in a personal document for interpretation. The company management also received a document, which summarized all the drivers' measurements. Expert measurements, with the same type of sampler, were also accomplished to evaluate the self-assessments. The geometric mean and the 95 percent confidence intervals of the measurements made by the drivers (29 measurements) was 0.17 (0.11-0.26), and by an occupational hygienist (8 measurements) 0.12 mg/m3 (0.04-0.37). The results show that the drivers technically can perform SAE. Interviews with the workers and the management indicated that some kind of organizational support within the company is needed to implement the method into the regular internal control of the working environment.