Epidemiological study, using interview and walk through survey methods, of potential hazards associated with laser operations in medical, industrial, commercial, governmental, research, and educational organizations. The study involved 200 establishments in Massachusetts, New Jersey, and California, employing 458,462 persons (with 279,317 working in plant, shop, or laboratory), and with 2176 lasers in use. Factors studied included potential risk, degree of hazard, engineering control, shielding, personal protective equipment, supervision, provision of medical services, maintenance of medical histories of previous exposures to nonionizing radiation, warning and safety devices and procedures, provision for eye and other medical examinations, possibility of accidental exposure, laser energy potential, and physical and chemical parameters of the environment. Results indicate a need for establishing criteria for evaluating and protecting the health of laser operators, and a need for better engineering and medical controls in the use of lasers. A scarcity of undocumented and unreported information concerning laser caused injuries is noted, as is the fact that most people who are exposed to lasers are not persons who work with lasers but are persons who happen to be in the area, indicating a need for better recordkeeping and reporting, and a need for provision of safety devices, areas, or rooms to prevent such exposure.