To assess the nature and work load of reviewers for the American Journal of Public Health, I surveyed a sample of 276 reviewers in the latter half of 1988, with a 96% response rate. Respondents reported reviewing papers for 274 other journals in 1987, 81% of which were monitored by the Science Citation Index or the Social Science Citation Index. They reviewed most often for The Journal of the American Medical Association (27%), the American Journal of Epidemiology (26%), and the New England Journal of Medicine (23%). The median number of journals for which they reviewed was 3.6, the median of their estimated review time was 2.7 hours, and the weighted average review time (adjusted for number of reviews) was 2.4 hours. The range of review time was broad and inversely related to the number of papers reviewed. Respondents donated an estimated 3360 hours of uncompensated labor to the American Journal of Public Health in 1987, and a total of 6439 hours (26.8 hours per reviewer) to reviewing for all journals. Of the reviewers for the American Journal of Public Health, only 31% were not listed as an author of a source publication in the 1987 Science Citation Index and only 15% were not cited.