He encountered two patients who displayed symptoms associated with spinal problems. One had suffered deafness associated with a spinal dislocation. On September 18, 1895 Palmer corrected the dislocation and his patient recovered his hearing. A second patient suffering from heart disease improved after adjustment of a spinal dislocation which Palmer believed exerted pressure on the nerves leading to the heart.
Palmer generalized from these experiences and founded chiropractic. His theory was that decreased nerve flow may be the cause of disease, and that misplaced spinal vertebrae may cause pressure on the nerves. Palmer founded a school, later the Palmer School of Chiropractic, in 1897, by 1902 the school had graduated 15 chiropractors.
Chiropractic was controversial from the beginning and many chiropractors, including Palmer, were prosecuted for practicing medicine without a license, although eventually it was recognized that chiropractors were not practicing medicine but chiropractic. D. D. Palmer sold the school of chiropractic to his son, B. J. Palmer and after several unsuccessful attempts to found a new school of chiropratic, died in Los Angeles on Oct. 20, 1913.