Dr. Watson is accepting new patients.
IBM says two medical applications using the Watson supercomputer are being offered for commercial use.
One application helps diagnose and treat lung cancer. The other helps manage health insurance decisions and claims.
Both applications take advantage of the speed, huge database and language skill the computer has already demonstrated. It defeated the best human "Jeopardy!" players on television two years ago.
Watson's medical training comes through pilot programs at WellPoint health insurance and Memorial Sloan-Kettering Cancer Center in New York.
IBM says the computer's database now includes 1,500 lung cancer cases from the hospital and 2 million pages of medical textbooks and journals.
The company says Watson also learned by being corrected when it came up with wrong answers as it was questioned by doctors.