The announcement comes as the retail giant faces criticism for what some believe is inadequate health care coverage for employees.
The drug program would be available to its employees and customers, even those with no health insurance.
"Wal-Mart is taking this step so our customers and associates can get the medicines they need at a cost they can afford," said Bill Simon, executive vice president of the company's professional services division, when announcing the plan at a Tampa, Fla., store, according to the Associated Press.
The company plans to launch the program Friday at 65 Wal-Mart, Neighborhood Market and Sam's Club pharmacies in the Tampa Bay area, and then expand it to the entire state in January.
The company said it would try to extend the program to as many states as possible next year.
The 291 generic drugs are commonly prescribed medicines for cardiac disease, asthma, diabetes, glaucoma, Parkinson's disease and thyroid conditions, reported the AP.
The savings vary: $4 for a 30-day supply of the generic form of the popular blood-pressure drug, Lisinopril, for example, is a third of the brand name price.
The prescriptions cannot be mailed, and are available online only if they are picked up in person.
The drugs would be sold at a loss to bring customers into the store, Simon said.
Shares of several drug store chains dropped after the news, including Walgreen Co., which fell 6 percent to $46.98, and CVS Corp., which slid 10 percent to $31.80 on the New York Stock Exchange, Reuters reported.
