To elucidate the situation of complementary and alternative medicines (CAM) in an occupational health setting, workers in a factory of a housing construction business were surveyed using self-administered questionnaires on their utilization of CAM in the past 12 months, out-of-pocket expenditures on CAM and ordinary western medicines (OWM), and reasons for the use of CAM. A total of 263 workers (84.3%) completed the questionnaires. Among them, 134 (51%) had received CAM therapy in the last 12 months: i.e. nutritional and tonic drinks (35.4%), supplements (16.3%), massage (13.7%), chiropractic or osteopathy (8.7%), health-related appliances (6.5%), herb or kampo (3.4%), aromatherapy (1.9%), acupuncture (1.9%), or other therapy (1.5%). Reasons for the use of CAM was "the condition was not serious enough to warrant OWM" and "expectation of health promotion or disease prevention" for 70 (51.9%) and 53 (39.3%) subjects, respectively. Average annual out-of-pocket expenditures for CAM and OWM were 17,500 and 21,300 yen, respectively. It seems important to further widen awareness and knowledge of CAM in occupational health.