To determine the number and distribution of exposures among workers exposed to silica dust in Vietnam, a cross-sectional study was conducted of the provincial Preventive Medicine Centers (PMCs) of 61 provinces, and data were collected from medical centers (MCs) of the Ministries of Construction, Industry, and Transportation. The PMC survey identified 112,956 exposed workers in 31 provinces. Ministry data identified 240,744 exposed workers. Quang Ninh province, with 50,000-70,000, had the highest concentration. These estimates provide a range of 40,000-350,000 exposed workers, supporting the development of a validated registry of silica-exposed workers, essential to the development of a program for silicosis prevention in Vietnam.