A description was presented of occupational questionnaires and three main categories of questions for use in community based retrospective epidemiologic studies. Occupational questionnaires used in case control studies had the objective of obtaining relevant exposure related information from subjects. The three categories of questions included general questions, occupation specific questions and exposure specific questions. An example of a general questionnaire eliciting information on job, tasks and environment in nonspecific terms was discussed, and the questionnaire was presented. This was used in a large hypothesis generating, multisite case referent study of occupational cancer in Montreal. Questions were grouped into five categories and were open ended. Each subject's potential exposures were coded by chemists, and semiquantitative indices were developed in terms of exposure level, frequency and reliability of exposure. Broad hypotheses were effectively generated using this questionnaire. Occupation specific questionnaires were developed from this study, eliciting specific details on the environment in specific jobs or occupations. A sample developed for welding, brazing and soldering occupations was presented. Advantages included improved coding, good acceptance by subjects, more uniform information collection and less demand on interviewers. A sample exposure specific questionnaire used in a French study of nasal cancer was presented. Questions covered specific agents or classes as well as information related to time of exposure. Errors in subjects' answers were more likely in occupation and exposure specific questions, and procedures to optimize validity were outlined. The authors conclude that such questionnaires considerably facilitate subsequent exposure assessments without being unmanageable for subjects or interviewers.