Twenty patients with symptoms of "environmental illness" were subject to a controlled study of deep versus superficial acupuncture. The patients were evaluated by a detailed questionnaire concerning their occupational, environmental, and medical history. Blood samples were taken as well. Patients were randomized to deep or superficial acupuncture. Both groups improved significantly in key variables during and after treatment. There were no group differences. There were no changes in biological variables apart from a gradual and continuous increase in serum cortisol and a decrease in neuropeptide Y, which was somewhat more accentuated in those receiving deep acupuncture. This rise in cortisol may have contributed to decreased dermal symptoms among the participants. It is hypothesized that the positive treatment results observed are partly due to weakening of the conditioned response, linking bodily symptoms to environmental agents. To date, a number of different methods have been tried in the management of patients with environmental illness. However, only rarely have the treatments been evaluated in controlled studies.