A medical doctor diagnoses the patient and writes prescriptions based on interview with the patient as well as blood tests, analysis of image data obtained from magnetic resonance imaging (MRI) and computed tomography (CT), information related to the patient's genes and so on. In giving the diagnosis, the doctor combines the information obtained through such processes with his or her own knowledge and experience. No matter how reputed a physician may be, the chances of them making a wrong diagnosis can never be zero.

With the recent progress in artificial intelligence, there has been much speculation that artificial intelligence could very well surpass a human doctor's ability to make diagnoses and write prescriptions.

In August 2016, the Institute of Medical Science at the University of Tokyo released the outcome of a case study to show how powerful AI can be. IBM's Watson AI program was fed with information contained in nearly 20 million medical articles related to cancer research and more than 17 million pieces of information related to pharmaceuticals.