This Work-Related Lung Disease (WoRLD) Surveillance Report is the fifth in a series of occupational respiratory disease surveillance reports produced by the National Institute for Occupational Safety and Health (NIOSH). It presents summary tables and figures of occupational respiratory disease surveillance data focusing on various occupationally-relevant respiratory diseases, including pneumoconioses, occupational asthma and other airways diseases, and several other respiratory conditions. For many of these diseases, selected data on related exposures are also presented. The 1999 WoRLD Surveillance Report has three major sections: 1) a section that provides data highlights and data usage limitations; 2) a section comprised of 13 subsections, each concerning a major disease category and (where available) related occupational exposures; and 3) a section of appendices that provide descriptions of data sources, methods, and other supplementary information. Similar to the 1994 WoRLD Surveillance Report, this report includes data on malignant neoplasm of the pleura, hypersensitivity pneumonitis, asthma, chronic obstructive pulmonary disease, respiratory conditions due to chemical fumes and vapors, and other work-related respiratory conditions, in addition to the pneumoconioses. This report updates pneumoconiosis mortality data published in the 1996 WoRLD Surveillance Report by addition of currently available data for 1993 through 1996. Pneumoconiosis conditions highlighted include asbestosis, coal workers' pneumoconiosis, silicosis, byssinosis, and pneumoconioses classified as either "unspecified" or "other," and all pneumoconioses aggregated. For many of the conditions reported on, the 1999 WoRLD Surveillance Report presents national and state summary statistics such as counts, crude and age-adjusted mortality rates, and years of potential life lost to age 65 and to life expectancy. Proportionate mortality ratios by industry and occupation, are based on the most recent decade of data from a subset of states for which usual industry and occupation have been coded for decedents. Also presented are U.S. state-level maps showing the geographic distribution of mortality and, for the pneumoconioses, tables and figures summarizing selected occupational exposure data for asbestos, coal and coal mine dust, silica dust, cotton dust, etc.