This study was undertaken to compare the agreement of occupational exposure assessment by a panel of occupational hygienists with a job exposure matrix and self-reported exposures in a community-based case-control study. We also investigated the intra-rater reliability and degree of attenuation of the hypothetical odds ratio of the panel in retrospective chemical exposure assessment. A panel of three occupational hygienists was recruited to assess exposure to chemicals for 5,620 jobs. The agreement between the panel, a job exposure matrix (FINJEM), and the self-reported exposures was then assessed. A further 172 jobs were resubmitted to the panel to assess intra-rater reliability. The kappa for intra-rater reliability ranged from 0.60-0.71. The agreement between the panel and FINJEM ranged from 0.07 to 0.46 (for similar exposures), and agreement between the panel and among the self-reports ranged from 0.00 to 0.48. Agreement between hygienists when rating exposure to the same chemical ranged from 0.48 to 0.57. Based on these findings, the degree of exposure misclassification by the panel where the true odds ratio was 2 would result in the observed odds ratio ranging between 1.70 and 1.88. The results indicated good intra-rater reliability for the hygiene panel. However, the agreement among the panel, FINJEM, and self-reported exposures was found to be only poor to fair. The attenuation of the odds ratios due to exposure misclassification by the panel was variable and dependent upon the exposure.