Doctors have some of the longest training periods of any profession, seldom entering independent practice until their late 20s or early 30s. Their extensive education is costly, but results in much higher than average earning potential. Medical salaries are among the highest in the country, but doctors in some specialties earn significantly more than their peers. Surgeons tend to earn more than physicians, but both are represented among the highest-paying disciplines in medicine.

Orthopedic Surgeons

Orthopedic surgeons treat injuries and illnesses affecting the skeleton, spine, skull, joints, and their supporting systems of muscle and tendons. They're among the highest-paid of all surgeons, especially orthopedic spinal surgeons. In its 2012 salary survey, the American Medical Group Association reported a median annual salary of $710,556 for spinal surgeons, with joint replacement surgeons next highest at $529,990. Spinal surgeons also topped the Medical Group Management Association's list of hospital-employed specialists, at an average salary of $714,088 per year. Hip and joint surgeons in that survey averaged $589,267.

Neurosurgeons

Neurosurgeons specialize in treating disorders of the brain and nervous system and are also among the most highly-paid practitioners. The AMGA salary survey reported the median annual salary for neurosurgeons as $656,250, second only to spinal surgeons. The 2011 MGMA study ranked neurosurgeons as the highest-paid specialty overall at an average of $767,627 per year, with pediatric neurosurgeons also in the top tier at $643,188. Among hospital-employed specialists, neurosurgeons were second to spinal surgeons at $701,927, while pediatric neurosurgeons averaged $656,282.

Heart Surgeons

Cardiovascular and cardiothoracic surgeons also rank among the most highly-compensated doctors. In the AMGA survey, cardiac and thoracic surgeons reported a median salary of $544,087 per year. The MGMA's 2011 survey reported an average salary of $762,846 for pediatric cardiovascular surgeons and $560,659 for their colleagues in adult surgery. In the hospital environment the gap narrowed, with pediatric cardiovascular surgeons averaging a still-high $681,408 per year and adult cardiovascular surgeons earning $656,282.

Dermatologists

Most dermatologists are well-paid, with a median salary of $397,370 in the AMGA survey. However, dermatologists who specialize in Moh's surgery -- removing skin cancers one layer of cells at a time -- earn even more. Among hospital-employed physicians, Moh's surgery specialists were among the top-paid at $586,083 per year.

Interventional Radiologists

Some non-surgeon specialists perform minimally-invasive procedures that border on surgery, using miniature instruments inserted through a tube or catheter. These include interventional radiologists, who use their expertise in medical imaging to guide instruments to the area needing repair. The AMGA survey reports their median salary as $485,277 per year, while the MGMA ranks them among the top hospital-employed physicians at $513,000 per year.

Invasive Cardiologists

LIke interventional radiologists, invasive or interventional cardiologists use miniature instruments inserted through a catheter to fix heart defects or blocked blood vessels. The MGMA survey reported an average salary of $586,765 for invasive/interventional cardiologists, also among the highest in the survey.