When Mildred Nelson moved the clinic to Mexico in 1963, Hoxsey stayed in Dallas in the oil business. In 1967, he developed prostate cancer. He took his own tonic, but ironically, it didn't work for him. Although surgery is fairly routine for prostate cancer, he refused to have it, fearing that the Dallas doctors would take their revenge on him on the operating table. Hoxsey spent his last seven years as an invalid, dying in isolation, nearly forgotten. He was buried around Christmas in 1974, without an obituary or tribute in the Dallas newspapers.

The Bio-Medical Center in Tijuana, a glass-walled mansion within sight of the United States-Mexico border, is an outpatient clinic only. Patients who arrive before 9 A.M. are seen without an appointment. They are given a complete workup, including a physical examination, lab tests, and X-rays, and have their clinical history taken. Patients are advised to bring existing medical records from other hospitals and facilities. After their appointment, which usually lasts one full day, sometimes longer, patients return home with enough Hoxsey medications and supplements to last several months. They are encouraged to make a follow-up visit after three to six months.

The herbal tonics, salves, and powders given are adjusted to suit the specific needs of each patient, taking into account his or her general health, the location and severity of the cancer, and the extent of previous treatments for it. The Hoxsey therapy is reportedly effective in alleviating pain in many cases.

Dietary specifications include the total avoidance of pork, vinegar, tomatoes, carbonated drinks, and alcohol. The forbidden foods are thought to work against the therapeutic action of the medicine. Patients are also told not to consume bleached flour or refined sugar and to ingest very limited amounts of salt. Supplements include immune stimulants, yeast tablets, vitamin C, calcium capsules, laxative tablets, and antiseptic washes. Patients are counseled to adopt a positive mental outlook and to assume complete responsibility for their own health. The clinic also offers chelation, immunotherapy, and homeopathy, as well as chemotherapy in extremely serious, life-threatening cases.

The types of cancer said to respond best to the treatment include lymphoma, melanoma, and external (skin) cancer. The clinic's patient brochure includes case histories of patients successfully treated for breast, cervical, prostate, colon, and lung cancers.

In 1965, Margaret Griffin of Pittsburgh was given one year to live by her conventional doctors. She had been having blackouts, and X-rays revealed that she had two tumors around her aorta. Exploratory surgery confirmed the existence of the tumors and also uncovered lesions in the right lung, a blockage of the superior vena cave, and metastases to the lymph glands. Thirty doses of cobalt radiation failed to arrest the growing tumors and made Margaret feel worse. As time went on, her face became puffy, she experienced difficulty breathing, and she felt that she was going steadily downhill.

Margaret decided to fly to Dallas to try the Hoxsey therapy. After visiting the clinic, she took four teaspoons per day of the herbal tonic for several months and followed the prescribed diet. She noticed no improvement, however, and was having serious doubts about the therapy's value. But after ten months on the regimen, her breathing improved, her strength returned, and she sensed a dramatic overall improvement. When she called her family doctor for a checkup, he refused to see her "because you didn't believe in my diagnosis." Subsequent X-rays taken by a different doctor indicated that the two tumors and related conditions were gone.