The general applications of epidemiology to the field of occupational health were reviewed. The three major types of epidemiological studies, descriptive, analytical, and experimental, were discussed. Occupational epidemiological studies included observational studies, such as the cohort, case/control, and cross sectional strategies, and experimental studies. Both prospective and retrospective cohort morbidity and mortality study designs were considered useful and effective in occupational epidemiology. However, the expense, time consumption, and large study size were viewed as limitations of the cohort study. Case/control studies were regarded as especially useful when either the disease of interest was rare or several occupations or exposures were related to the disease of interest. Limitations of this study design were listed as weak exposure estimation techniques, indirect calculation of incidence rates, and selection and recall biases. Cross sectional studies were considered appropriate for investigating subtle health effects which may not be officially recorded, generating hypotheses, and planning health services. Ecologic study designs were described as crude methods for determining the relationships between either occupation or environment and disease. Meta analysis was the systematic pooling of data from multiple studies in order to generate comprehensive conclusions. The importance of routine occupational surveillance for the establishment of program objectives, public policies, research priorities, and prevention strategies was also discussed. Molecular epidemiology was considered increasingly important with the continued application of biomarkers. The author concludes that while scientific advances may alter the epidemiological approaches, the primary aims of occupational epidemiology will continue to be the identification, validation, and prevention of occupational diseases.