The Guangzhou Occupational Cohort Study was established to investigate the mortality of workers in relation to smoking and occupational exposures in Guangzhou, China. The cohort is comprised of 2 sub-cohorts: over 82,000 factors workers, and over 86,000 drivers. All participants were 30 years old or above when entering the cohort. Initial details on participants was obtained from the Guangzhou Occupational Diseases Prevention and Treatment Center, which was responsible for occupational health surveillance of workers in the region. Workers with records from 1988-1992 were included in the cohort, whilst for drivers, those examined from March-December 1992 were included. Vital status was followed up through data linkage until the end of 1998 for the worker participants, and September 1999 for the driver participants.