The primary objective of the medical-social component of the National Mesothelioma Surveillance Program is to evaluate and improve the management of occupational disease cases among patients with pleural mesothelioma for whom occupational exposure to asbestos has been identified. With this in mind, the procedures for recognizing pleural mesothelioma as an occupational disease (OD) in the departments covered by the PNSM were evaluated and compared to those in other French departments under the General Social Security Scheme (RGSS). In 18 of the 21 departments currently covered by the PNSM, 449 cases of pleural mesothelioma were "not excluded" by the French College of Pathologists Specializing in Mesothelioma (Mésopath group) between 1999 and 2001, and 68% (n=306) fall under the RGSS. A declaration of occupational disease (DMP) was filed for 62% (n=189) of these subjects, most of whom (91%) received approval from Social Security. Among the 38% (n=117) of subjects who did not apply for recognition as an occupational disease, 39% (n=46) are considered to have been exposed to asbestos based on the findings of the etiological investigation conducted as part of the PNSM. The analysis conducted on the 4 PNSM departments with 30 or more mesothelioma cases during the 1999–2001 period shows that the proportion of occupational disease recognition applications not filed for subjects covered by the RGSS varies significantly from one department to another (from 13% in Loire-Atlantique to 46% in Isère). Data collected from 18 PNSM departments and 64 non-PNSM departments for the years 1999–2000 show a high rate of recognition as an occupational disease for cases covered by the RGSS who underwent a DMP, exceeding 90% in both cases. The proportion of reported cases appears higher in PNSM departments than in non-PNSM departments. Indeed, the ratio of the number of DMPs to the number of cases receiving coverage for pleural mesothelioma (ALD3O) is higher (1.18) in PNSM departments where the number of ALD3O cases in 1999–2000 exceeded 15, than in the 4 non-PNSM departments meeting the same criteria (ratio = 0.74). A "PNSM effect" appears to be observed in the DMP process for individuals covered by the RGSS. The continuation of the medico-social component will allow for an analysis of changes in the procedures implemented following a diagnosis of pleural mesothelioma, particularly following the establishment of the Asbestos Victims Compensation Fund (Fiva). (R.A.)