Two categories are available in the field of medicine, to the exclusion of practitioners of complementary medicine: allopathic and osteopathic medicine. Doctors of allopathic medicine are often referred to as medical doctors (M.D.) and doctors of osteopathic medicine are called osteopathic doctors (D.O.). Even though both types of doctors do the same things including treating patients with drugs, obtaining medical specialties, and performing surgical procedures, they do differ in philosophy, approach to medical practice, and education.

Allopathic and osteopathic medicine have slight differences in philosophy when it comes to the focus of treatment and the practice of medicine in general. Basically, allopathic medicine places emphasis on disease and treating with drugs or surgery, while osteopathic medicine is centered around holistic treatment which takes the whole person into account. Osteopaths believe that it is important to work with the natural healing power of the human body and that the musculoskeletal system is essential to health. Both types of medicine include a preventative emphasis, but osteopaths tend to apply it to practice more.

Career preparation for both allopathic and osteopathic medicine is typically identical. Requirements for medical school includes completion of a four-year undergraduate degree, medical school which also lasts four years, and several additional years are spent in residency training. Where medical school curriculums diverge is that osteopathic medicine mandates an additional training component in something referred to as osteopathic manipulative medicine (OMM). With OMM, the osteopath uses his or her hands to treat patients suffering from circulation problems, range of motion limitations, as well as pain in the joints and muscles. Often confused with alternative therapies like massage and chiropractic care, OMM involves deep tissue manipulation of organs, blood vessels, and supportive structures like the bones or ligaments.

In terms of practice prevalence, as of 2011, allopathic and osteopathic medicine are not equal, as there are discrepancies regarding practice rights. Although the practice of osteopathic medicine occurs in many parts of the world including Canada, Europe, and the U.S., full licensing rights are not extended in several countries. In the U.S., DOs are permitted to practice medicine to the same extent as MDs, in all of its regions. The same is also true for Canada and most regions in South America, but, for places like France, Jamaica, and New Zealand, osteopathic practice is limited to OMM or even completely prohibited. Due to training equivalency problems, no osteopath trained outside of the U.S. is extended a license to practice as of year 2011.