Wal-Mart Stores said it will contract with local hospitals and other organizations to open as many as 400 in-store health clinics in the next two to three years.
Should current market forces continue, the world's largest retailer said up to 2,000 clinics could be in Wal-Mart stores over the next five to seven years.
Wal-Mart said the effort marks an expansion of a pilot program it started in 2005, when it leased space within its stores to medical clinics. Currently, it said 76 clinics are operating inside Wal-Mart stores in 12 states.
It has said the clinics are expected to boost the health of its shoppers and should also help sales by drawing consumers into its stores.
Wal-Mart has endured criticism over the years from labor unions that say it pays inadequate wages and pushes employees onto government aid programs. The company has tried to counter such attacks, taking steps such as selling generic drugs for $4 per prescription in many areas.
Earlier this year, Wal-Mart joined with the 1.8 million-member Service Employees International Union, one of its most vocal labor foes, to call for universal health-care coverage for all Americans by 2012.
"We think the clinics will be a great opportunity for our business. But most importantly, they are going to provide something our customers and communities desperately need -- affordable access at the local level to quality health care," said Wal-Mart Chief Executive Officer Lee Scott in a statement.