OBJECTIVES. Follow-up of California blood lead registry reports, 95% of which are of occupationally exposed adults, can guide interventions at specific high-risk work sites and measure the impact of targeted, industry-specific interventions. METHODS. A protocol was implemented to follow up the most severe case reports (> or = 2.90 mumol/L) and establish a statistical database for descriptive analysis. RESULTS. From 1987 through 1990, the California Department of Health Services received 17,951 reports for 4069 civilian, noninstitutionalized adults employed by at least 328 companies. Of 232 incident case subjects with severe lead toxicity (> or = 2.90 mumol/L), 182 were successfully traced and interviewed. Index case subjects were mostly male (95%) and disproportionately Hispanic (46%); 35% lived with children aged 7 or younger, and 10% had been hospitalized. Ninety-four percent involved overexposures at work sites that lacked medical removal (50%), ventilation (36%), appropriate respirators (62%), training (64%), clothing changes (45%), or showering (60%). CONCLUSIONS. Well-known risk factors for occupational lead poisoning clustered at the work sites of index case subjects. Despite standards of the Occupational Safety and Health Administration, lead overexposure in California adults remains a significant public and occupational health concern.