Data from 11 previously published mortality studies were utilized to compare the known occupation and industry of 3789 individuals, derived from company personnel files or union records, with the occupation and industry listed on their death certificates. Emphasis was placed on 2198 individuals having ten or more years of work experience (average 18 years). The variables in this study included duration of employment, total work time, number of years between last employment and death, place of death, age at death, year of death, sex, race, blue collar or white collar status, and native born or foreign born. Three digit census codes assigned from each individual's work history were compared with three digit census codes derived from the death certificate. For long term workers the probabilities of the known occupation and known industry being listed correctly on the death certificate were 65 percent and 70 percent, respectively. Probabilities were higher for white workers and lower for female and nonwhite workers. The authors suggest that the use of occupational data on death certificates may be most useful when considering long term white male workers in well defined occupations or industries.