Twenty disabled patients with recurrent intractable nontraumatic phlebitis were studied. The patients were divided into two groups and matched for age and severity. The control group was continued on their standard anticoagulant regime, bed rest and support hose. The other group was placed in an especially designed Environmental Control Unit (ECU) where all air, food and water could be controlled. These patients were taken off all medication and not fed until the leg pain and swelling disappeared, which was four to seven days. The patients then showed specific sensitivities to foods and ambient subthreshold doses of inhaled chemicals such as formaldehyde less than 0.2 ppm, phenol less than 0.0024 ppm, chlorine less than 0.33 ppm, petroleum alcohol less than 0.5 ppm and pesticide (2,4 DNP) less than 0.0134 ppm under controlled double-blind challenges. Eight out of 10 patients had their phlebitis reproduced in this manner. When in the symptom-free state, these patients were required to ride an exercycle at 150 kpm for one mile daily to demonstrate absence of phlebitis (none could walk across the room prior to examination). The five-year follow-up in the group showed two 48-hour episodes of phlebitis cleared by home bed rest and food abstenance. In contrast, the control group had more than 60 episodes of phlebitis at home and 41 episodes in the hospital. Medical costs in these comparable groups showed a differential of $20 per patient in the Environmental Control Unit treatment versus more than $20,000 per patient in the control group over the five-year follow-up.